Construct

"Construct" is a map referenced in the Halo 3 Beta code. It was then confirmed in a leaked photo, and then explored in two videos. It is a forerunner complex, with an entire open side, showing many extrusions, which may be docking bays of some type. Below is a large ocean. Sentinels float out far from the level, but can be destroyed with long range weapons.

The level is completely symmetrical, which is multi-leveled. The center is mostly open, while the sides have many floors which are connected by ramps, and sometimes gravity lifts.

It appears to be a confirmed in a leaked sceenshot.