Mausoleum is considered to be a remake of 'Backwash' (Halo 2 Maptacular Map Pack), maybe in the same way as Last Resort is a remake of Zanzibar.
Since it came out that I am not good in forging hills and fog I decided to make the remake structures larger than in the original for better gameplay (shorter lines of sight).
Most of the original jumps are possible and due to the size I added and changed some things (like the multiple trees area).
The layout is simple: two bases devided by a tower that can be entered via four passages on the ground and on the first level. To get to the other base you can choose an open route ('multiple trees') or the safer sword passage, besides the way through the tower.

This map supports all gametypes though it is best suited for Oddball, Slayer and KotH.
Weapons and grenades on Mausoleum are nearly the same as on Backwash
(the two Shotguns got replaced by Maulers since the Shotgun is stronger in Halo 3 and they were set very close to each other, so, dual-wield the Maulers):

2x Sentinel Beam [180s]
1x Sword [180s]
1x Covenant Carbine [30s] (max. on map = 4)
1x Battle Rifle [30s] (max. on map = 4]
1x Brute Shot [90s]
2x Plasma Pistol [60s]
6x Plasma Rifle [30s]
4x SMG [30s] (max. on map = 8)
2x Mauler [90s] (max. on map = 4)
2x Pistol [30s] (max. on map = 4)

6x Frag Grenade [30s]
6x Plasma Grenade [30s]

1x Active Camo [180s]

Pics (haloscreenshots.com):

http://haloscreenshots.net/gallery/BC264C93268C205D7DF7D809FA403C54/

http://haloscreenshots.net/gallery/01E5D97542A33F52A02256FC415707A5/

http://haloscreenshots.net/gallery/C796AF8A5F40440B71C94C5DBD89B28A/

http://haloscreenshots.net/gallery/A896BEB16EA1E70C0826CE8DB4E47FBF/

http://haloscreenshots.net/gallery/9749BC22823262A9F06EED8AD33697ED/