The Constitution-class, also known as Starship class, was launched by Starfleet in the latter half of the 23rd century in the alternate timeline. This class of starship differed greatly from its prime universe counterpart in both configuration and scale, but was exemplified by the USS Enterprise in both realities. (Star Trek)
The alternate Constitution-class dates back to at least 2255 with the construction of the USS Enterprise in Riverside, Iowa on Earth. The design of the starship class markedly differed from its prime universe counterpart following the temporal incursion by Nero and the destruction of the USS Kelvin in 2233. (Star Trek)
Following its launch in 2258, the Constitution-class USS Enterprise served the United Federation of Planets in a variety of tasks, including survey missions and military operations. The class wasn't placed into long duration service until the Enterprise was assigned a five-year mission after 2259. (Star Trek Into Darkness)
In that year, a space dock manifest display graphic in the office of Admiral Christopher Pike included two Constitution-class icons identified as AF and VH-5. (Star Trek Into Darkness, production art)
The Constitution-class starship followed the traditional saucer section-engineering section-warp nacelle layout common to most Starfleet vessels, but dwarfed in size many starship classes in service alongside it. Where the prime universe Constitution-class of the same period featured a similar, but geometrically simplified construction, the alternate Constitution-class displayed a more organic physical arrangement. The hull had iridescent plates and a subtle Aztec pattern. Escape pods could be launched from the port side of the neck. (Star Trek)
The uppermost section of the ship composed the primary hull - or the saucer section. The saucer section was joined to the engineering hull by a stout "neck" that terminated along the dorsal side of the engineering hull fore of the shuttlebay, which was able to hold at least twenty shuttlecraft despite being shorter than the ship's bow.
The engineering hull was conical in shape, capped by the main deflector to the fore and the main shuttlebay to the aft. The shuttlebay 2 launch bay door was located forward of the main shuttlebay on the starboard side below the warp nacelle pylons. The deflector dish's center would open and close when entering and exiting warp. The shuttlebay and flight decks comprised a large portion of the engineering section as did main engineering and its related hardware. (Star Trek; Star Trek Into Darkness)
The ship's two warp nacelles were mounted by pylons to the port and starboard sides of the ship's engineering hull, each at a near-forty-five degree upward angle, fore of the ship's flight deck doors. The nacelles featured a flared housing around the Bussard collectors, which dimly glowed blue, and the aft section contained components that extended and retracted when entering or exiting warp. The uppermost section of the nacelles were parallel in height to the ship's bridge. The life support center of this class was located aft of the warp nacelles. (Star Trek Into Darkness)
Inside the Constitution-class, upper sections were predominantly white with polished black floors, while the lower decks progressively displayed less aesthetic design. Crewman workstations often had little personal space to work in. The engineering decks consisted of conduits, tanks, and catwalks spanning each section. Ladders located in corridors allowed crew members access to spaces above and below their current location. (Star Trek; Star Trek Into Darkness)
Command and control systems
The Constitution-class's primary command center, the main bridge, was located on top of the vessel's primary hull, on A Deck. From here, the commanding officer supervised the entire starship's operation from the command chair, located behind the helm and navigation consoles, and was flanked on all sides by stations controlling the vessel's primary functions. A large window augmented with computer displays served as a viewscreen, located at the fore of the bridge.
Piloting and navigation functions were carried out at the helm console, located in the center of the bridge. This console consisted of three main sections - navigation and ops stations and primary tactical control. Behind and flanking the captain's chair were two forward-facing workstations for a junior science officer (port) and a junior communications officer (starboard), supplemented by free-standing data screens. The senior science officer's and com officer's stations were located along the starboard back wall of the bridge. Numerous other stations occupied the walls of the bridge as well, generally populated by engineering division crew members to starboard and science division personnel to port.
All operations on the bridge and elsewhere aboard the Constitution-class vessel were performed on touch-screen consoles and displays. The ship's primary computer core was capable of being linked to cybernetic personnel for analysis. (Star Trek; Star Trek Into Darkness)
The Constitution-class cruiser was outfitted with a single twin-exhaust impulse drive unit mounted at the back of the saucer section where the primary and engineering hulls join. The saucer section of the ship was also fitted with numerous ventral RCS thrusters which could operate in space, in a planetary atmosphere and - if required - within a planet's ocean. (Star Trek, Star Trek Into Darkness)
Warp propulsion was powered by the warp core that comprised of multiple warp reactors. Energy from the matter/antimatter intermix was fed to the two warp nacelles. When going to warp, the impulse reactors would deactivate and the tail of the warp nacelles would expand when the ship jumped to warp speed. The multiple warp reactors could be ejected in cases of extreme emergency.
Unlike the ship's prime reality counterpart, both impulse and warp drive were regulated from the bridge, with engineering serving as monitoring and maintenance mid-flight. If not disengaged, external inertial dampeners will negate acceleration to warp velocity. (Star Trek)
By 2259, the several smaller reactors were replaced by one large warp core that was housed in a large hemispherical containment unit, with a large electrical coupler at its center allowing distribution of power to the rest of the ship. The warp core was isolated from the rest of engineering by several radiation doors. Sometime later, a wider, single-exhaust impulse engine was installed on the Enterprise. The fins on the warp nacelles were also refitted with new sets of warp drive components. (Star Trek Into Darkness)
Main engineering was aesthetically bare-bones. The entire section was occupied by and controlled machinery required to keep the ship operating. Pipes, conduits, and tanks typically occupied the floor while catwalks spanned the space overhead. The original warp core design consisted of multiple dilithium crystal chambers, which were replaced a year later with a single warp core unit. (Star Trek; Star Trek Into Darkness)
The saucer section of the Constitution-class was armed with six phaser banks, all with twin phaser turrets. Each of the twelve ball-turrets was capable of emitting a rapid fire barrage of phaser blasts. The banks were located on the dorsal and ventral sides of the saucer section. The phasers could be used for assault on an enemy ship or as point defense against enemy torpedoes. (Star Trek)
The torpedo bay and main forward torpedo launcher were located on the flared section of the neck connecting the primary hull and the secondary hull, and at least 12 photon torpedoes could be loaded simultaneously into torpedo tubes. The torpedoes could be fired rapidly in a barrage from the launcher. The ventral aft torpedo launcher was located at the bottom mid-section of the secondary hull. (Star Trek)
In 2259, a deck of the engineering section on the Enterprise was converted into a large weapons bay and refitted with several new broadside torpedo tubes on both sides of the secondary hull along the longitudinal axis. These new tubes were capable of being loaded with the larger new advanced long-range photon torpedoes developed by Section 31 of Starfleet in preparations for a war with the Klingon Empire. (Star Trek Into Darkness)
In 2259, the Constitution-class was equipped with metaphysic shields as a part of its defensive array. The shield strength of the ship was indicated by diburnium-osmium levels that gave the ship protection from threats, such as phaser and photon torpedo fire from enemy targets. Shielding was divided into bow and aft deflectors. (Star Trek Into Darkness, display graphic )
The transporter room aboard the Constitution-class occupied a corridor room of the saucer section. The back of the room was a circular alcove containing the transporter pad. The blue steps of the transporter glowed red when in use. The transporter control system was located just inside the room's entry, and was shielded from the transporter pad by either a glass or transparent aluminum wall. The control system was illuminated by lamps attached to the control board by flexible necks.
Transporter target lock was attained by using a joystick control to lock onto the target(s) designated for transport. Operation of the transporters typically required that the target not move, relative to its own surroundings, before it could be dematerialized. The system could be used to lock on to a moving target and negate the target's momentum upon rematerialization, but using the system in such a way required a highly skilled operator. The transporter chief typically wore a miniature heads-up display in front of the left eye. (Star Trek; Star Trek Into Darkness)
- USS Enterprise (NCC-1701)
For the alternate-reality Enterprise depicted in the films Star Trek and Star Trek Into Darkness, the Constitution-class was designed by Ryan Church, based on the original Constitution-class design, which was conceived by Matt Jefferies. On the Starships Blu-ray featurette, it is acknowledged that the redesign has elements of both previous versions of the Constitution-class Enterprise, from Star Trek: The Original Series and the first six Star Trek films respectively. The redesign was also inspired by the sleekness of a hot rod car. For Star Trek Into Darkness, Industrial Light & Magic digitally generated the Constitution-class model using a new CGI renderer – Solid Angle Arnold, in conjunction with the Katana lighting tool released by computer graphics and visual effects software developer The Foundry. (Cinefex, No. 134, p. 72)
The bridge, upper corridors and turbolift, transporter room, and sickbay of the revised Constitution-class were built as sets at Paramount Pictures. According to Production Designer Scott Chambliss and others on the Star Trek film's Blu-ray and Star Trek - The Art of the Film, the ship's white upper levels were inspired by Pierre Cardin's architecture, an approach which evidently continued to the brig in the sequel. Noted Roger Guyett, "We had somehow managed to negotiate the dangerous waters of redesigning the Enterprise – adding detail and making it feel more modern." Whereas re-envisioning the Constitution-class for the film Star Trek represented a major design challenge, the class remained relatively unaltered in Into Darkness, though the filmmakers of the latter movie decided to explore the design in more detail. "We used the same sets, redressed and updated," noted Visual Effects Producer Ron Ames. (Cinefex, No. 134, p. 72)
The more industrial lower levels of the ship were filmed at a Budweiser brewery. The filmmakers filmed the engineering rooms on location, instead of building a set, because they lacked money. For the sequel, the filmmakers shot the warp core scenes at the more advanced-looking National Ignition Facility in California. 
The ship's dedication plaque lists the Enterprise as Starship class, the same as its prime universe counterpart, while the ship's dossier on the official movie website identifies the Enterprise as a Constitution-class heavy cruiser.  The Enterprise is canonically identified as a Constitution-class starship in a viewscreen graphic from Star Trek Into Darkness, seen on the main bridge of the USS Vengeance.  The website also notes that she is being "held in Beta Testing Ward 956 – approved for combat." The maximum speed of the Enterprise is given as warp 8.
Co-writer Roberto Orci explained the logic of having the Enterprise being built on Earth rather than in space, noting that components of the ship can be built on Earth and assembled anywhere and that the Enterprise is not "some flimsy yacht that has to be delicately treated and assembled." He also feels that it makes more sense to construct the ship within a natural gravity well, rather than an area that will require an artificial gravity field.  Orci made these comments after a teaser trailer that was released prior to the film included footage, unseen in the movie itself, that showed the Enterprise under construction and being welded upon.
According to the Enterprise Tour and the "Starfleet Vessel Simulator" bonus feature, which was available on a Blu-ray Disc, the crew size of the Constitution-class is 1100. According to the two sources, the internal configuration was as follows:
The primary hull houses the main bridge on the A deck, the ship's crew quarters are on D and E decks, F deck hosts the transporter room and the sickbay is located on G deck. The primary hull also includes the impulse drive and the science laboratories. The section is protected by phaser turrets on the ventral and dorsal sides. On the main bridge, there are fourteen seated crew positions. Several escape pods are also located in the section.
The secondary hull houses the ship's engineering systems on N and O decks and the hangar deck, capable of housing sixteen shuttlecraft is on R deck. The secondary hull also houses the main torpedo launcher, navigational deflector, and living and work spaces for the engineers. This section is protected by phaser turrets, a forward facing main torpedo launcher on the neck pylon, and an aft facing torpedo launcher located on the ventral side of the hull in a recessed alcove. Several escape pods are located in this section, with a majority of them being in the neck pylon. There is a tractor beam located at the rear of the ship which assists shuttles during landing into the hangar deck.
In both sections, there are corridors and turbolifts. Corridors are equipped with communication terminals, safety features designed to keep the crew alive during emergencies, and emergency power supplies. There are access panels adjacent to doors that can restrict access to a compartment. There are passenger and freight turbolifts on the ship.
The warp nacelles house the ship's bussard collectors, field coils, and warp coils. The collectors capture interstellar hydrogen via an electromagnetic field and convert the gas into fuel for the ship by a nuclear fission process. The field coils transmit subspace emissions that can be used for the sensor and communication systems. Plasma gases that are generated by the warp coils are expelled by exhaust ports located at the rear of each nacelle.
Before the release of Star Trek on Blu-ray, there were several conflicting, early, behind-the-scenes accounts regarding the scale of the Constitution-class starship.
- 1200 meters: On 10 September 2007, a metric size-chart depicted the ship to be 1200 meters in length (3937 feet). This early chart was reproduced for Star Trek - The Art of the Film (p. 145).
- 1524 – 914.4 meters: In October 2007, the size of the Enterprise was still very much undefined. According to Star Trek illustrator John Eaves, at that time, it was considered to be somewhere between 3000 and 5000 feet (914.4 to 1524 meters).  
- 914.4 meters: On 1 May 2009, a Post Magazine article entitled Star Trek Returns – which included an interview with Russell Earl, the co-VFX supervisor of Star Trek – cited the ship as being 3000 feet in length (914.4 meters). 
- 762 meters: On 14 January 2008, an Industrial Light & Magic size chart of the Enterprise depicted the ship to be 2500 feet (762 meters) in length. Alex Jaeger shows this chart in the Starships bonus feature on the Star Trek Blu-ray release. Before the release of the Blu-ray (on his blog), Jaeger had quoted the same figure from an unspecified early chart, adding that the size may have later been somewhat reduced.  Experience the Enterprise also used these dimensions: Length: 2500 feet (762 meters), saucer diameter: 1100 feet (335.3 meters) and height: 625 feet (190.5 meters) 
- 725.35 meters: In November 2009, when Star Trek was released on Blu-ray, the length of the ship as 2379.75 feet (725.35 meters) was a more prominently portrayed figure in the Starships bonus feature. It was also the size given in Star Trek - The Art of the Film (p. 160, Note 4). Gizmodo blog writer Jesus Diaz was the first to reveal this number, citing his source as being "David B." of Bad Robot Productions.  Bob Plant of Round 2 Models provided the exact same figure, saying it was specified by the licensor of their planned model kit, who in turn had obtained it from ILM.  "My gosh, yes – JJ did make the ship that big. According to our (very reliable) source, the 'actual' size of the ship is 2379.75 feet long. It’s a whopper. A 1/2500-scale kit would put the assembled model at about 11.5″ inches long, which is just right for standard size packaging."  In a separate interview, Plant also asked Enterprise designer Ryan Church, who said that he was unable to address the issue of the changed size (compared to that of the original series Enterprise) and that ILM or J.J. Abrams could probably better answer the question. 
- 718.4 meters: On 26 May 2009, in an article in CG Society on ILM's visual effects work for the film Star Trek, the length of the ship was stated to be 2357 feet (718.4 meters). "One challenge was to sell the weight and scale of the ships that ranged from a 30 foot shuttle to the new Enterprise at 2,357 feet long, to the nemesis ship, the Narada, five miles long." 
- 609.6 meters: On 13 May 2009, in an interview for Studio Daily, ILM model supervisor Bruce Holcomb stated that the ship was 2000 feet in length (609.6 meters). 
- 365.8 meters: In July 2009, in the article on Star Trek in Cinefex #118, it was noted that "the reconfigured ship was a larger vessel than previous manifestations — approximately 1,200-feet-long (365.8 meters) compared to the 947-foot ship (288.6 meters) of the original series." The statement is immediately followed by a quote from Visual Effects Art Director Alex Jaeger: "Once we got the ship built and started putting it in environments, it felt too small. The shuttle bay gave us a clear relative scale — shuttlecraft initially appeared much bigger than we had imagined — so we bumped up the Enterprise scale, which gave her a grander feel and allowed us to include more detail."
- 294 meters: In May 2013, a 1:500 scale model was released by Revell of the USS Enterprise. The model was 588 millimeters long. This equals to a length of 294 meters or 965 feet. 
The video game Star Trek D-A-C features various named Constitution-class ships. According to the game, the ships could also be armed with quantum torpedoes in the late-2250s. According to the mobile phone video game, Star Trek: The Mobile Game, the Enterprise was equipped with a massively powerful phase cannon capable of slicing through and destroying multiple starships.
- Primary hull: Computer Core P/S, Impulse Reaction System, Junior Officers Quarters, Lower Sensor, Main Bridge, Main Sickbay
- Secondary hull: Antimatter Fill Port, Battle Bridge, Cargo Bay Aft, Cargo Conveyor, Eng Computer Core, Main Engineering, Main Shuttle Bay, Photon Torpedo Launcher bow and aft, Primary Nav Deflector, Tractor Beam Emitter, Warp Reactor core
- Warp Nacelles: Field Geometry Sensor, Subspace Field Coil System