Tycho City is located on Earth's Moon and probably part of the Lunar colonies. The city has self-contained atmosphere and artificial gravity (presumably to Earth standard).
By 2373, it was large enough to be seen from Earth at daytime, since Commander William Riker missed the familiar sight of the city, while looking at the Moon during his mission to the year 2063. (Star Trek: First Contact)
Cadet Dorian Collins was from Tycho City. (DS9: "Valiant")
- Named either after the Danish astronomer Tycho Brahe of the 16th century, or the lunar crater Tycho.