Cirriform Veil is an Extermination/2v2 map set on the Gondola of Halo 2's Quarantine Zone. It's small and therefore plays very fast for an extremely intense Extermination game. There are several methods to traverse the three levels which may not be apparent at first glance, and there are several alternate clamber routes for brave players.
Updated 2018-03-16: Added new geometry including 4 additional routes, more cover between sides, a new lift from level 1 to level 3, made use of the bottom level back door.
The map's description explains the unique setting and structural changes to the Gondola: "The Resistance retrofitted Halo's Gondolas to traverse the skies when they learned Cortana and her Wardens were blind to ancient technology".