Iconia was an uninhabited planet. In the distant past, this was the homeworld of the extinct Iconian civilization, located in what was now the Romulan Neutral Zone. The planet was devastated by a massive orbital bombardment approximately 200,000 years ago. The Iconians were believed to have been annihilated, although a part of the population may have escaped through their gateways.
The precise location of Iconia was lost to history until 2365, when an artifact bearing an ancient starmap was discovered in an archaeological dig on Denius III. From there, Captain Donald Varley of the Federation starship USS Yamato was able to locate Iconia, and chose to violate the Neutral Zone to reach the planet so as to prevent Iconian technology from falling into Romulan hands. After the Yamato was destroyed by an Iconian software transmission, the USS Enterprise-D and the Romulan warbird IRW Haakona both traveled to Iconia, where Captain Jean-Luc Picard had the last operational structure on the surface destroyed. (TNG: "Contagion")