Infinite Virtue Station
From Halo: Daybreak
The Infinite Virtue Station is perhaps most remarkable for the ultimate irony of its name, so infamous is it as a den of scoundrels and debauchery. Deep in the past, it was the secret pet project of a megalomaniacal Hierarch who initially commissioned it as a mighty superweapon. However, progress was slow due to the project's secrecy, poor management and arguably unworkable design (it was suspected that the weapon could never have worked as intended anyway), and following the end of said Hierarch's term, the mostly empty husk of the weapon was forgotten for ages until it became a trade port and waystation as the Covenant's reach expanded around it.