Damnation

Summary
Damnation is a multiplayer map in Halo 1. It has a Sniper Rifle facing the Oversheild, two shotguns, plasma/human pistol, and assualt riffles. This map wasn't remade in Halo 2 mainly because it would be less interesting without Fall Damage. It contains a flood dripping effect much like those in the campaign, and it bears the layout of a covenant research laboratory. It is higly popular on the oddball setting.

Bungie.net Description:
Damnation

A covenant structure that was used to control water flow into a section of HALO. Damnation is one of the few non-symmetrical maps in HALO, and it incorporates both a high and low flag base. During CTF events stay close to the flag locations and snipe across the high teleport road and the low damn crossing. Communicate well and the flag is yours, as it is easy to attack the flag bases from multiple sides at once. The rocket launcher is located in the middle of the lower corridor below 'shotgun alley', so be sure to pick it up during your travels. In addition, use the two sniper rifles to surprise and effective suppress opponents.

There's a good hiding place near the uplink crate.

Watch your step! There are a lot of areas on Damnation where you can walk off a ledge and die. Pipes, on the other hand, can be fun places to hang out and get the drop on someone.

You can't hop to the pit area from the falls bridge area, but you can do it the other way.