The Vulcanis Lunar Colony was a Vulcan settlement.

Tuvok was born in the Vulcanis Lunar Colony on stardate 38774 (2264). (VOY: "Unimatrix Zero, Part II", "Flashback")

This colony was only mentioned in dialogue.
It is not clear where this colony is, since Vulcan has no moon. The adjective "lunar" is usually associated with Luna, Earth's moon.