EDIT (21st feb 2011) New, performance optimised version available: http://www.bungie.net/Stats/Reach/FileDetails.aspx?fid=14941906&player=MrSaddo

I guarantee that if you like BTB you will enjoy this map.

This is a full rebuild from scratch of my original Hog's Den map. (ORIGINAL THREAD HERE)

Rebuild improvements include:

Simpler, more efficient design using fewer forge pieces means there are very few frame rate issues, flicker, screen lag etc.
Base lower levels have much wider corridors.
Base upper levels have new area which overloocks the central area.
Vehicle bay now has ramp to top level allowing defenders to access upper levels of their base more easily.
Minor spawn-killing issues around vehicle bay have been resolved by placing brace tunnels further out to provide more cover.

The map consists of two very large identical bases placed in diagonal symmetry. They are connected by a main road (known as the rocket road) that runs through each of them. Each base has two levels and multiple routes through and around it.

Overview shots showing main exterior areas:

The last pic is to illustrate the overall layout. Don't worry about the flat and barren nature of the roof tops as you never get to see this area.

Each base consists of the generator room, the control room, the hog tunnel and the vehicle bay. These areas are connected by a simple series of corridors and stairways:

Control room.: This provides a tactical position for snipers and DMRs, but can be vulnerable to attack from behind if other parts of the base are neglected.

Generator room: This area is usefull for defending most infantry attacks through the base. Control this room and the enemy will be forced to take a longer route to his objective.

Vehicle bay: this area is exposed to enemy warthogs if you allow them to get behind your base. The flag and assault objectives are in this area.

Hog tunnel: This area will give the enemy fast access to the rear of your base if you neglect its defence. Concussion rifle, which spawns in the upper corridors will give hogs a real headache in these tunnels.

Each base has a turret outpost off to the side. do not underestimate the strategic strength of this position as the gunner is well defended vs incoming vehicles.

Vehicles on map:

Warthog x4 (60s)
Mongoose x4 (30s)
Ghost x2 (60s)

Weapons on map: (spare clips, spawn time)

AR x4 (2, 30)
DMR x6 (2, 30)
Rockets x1 (1, 180)
shotgun x2 (2, 90)
Sniper x2 (2, 120)
Mounted machin gun x2 (-, 120)

Concussion rifle x2 (2, 120)
Needle rifle x4 (2, 30)
needler x2 (2, 90)
plasma pistol x4 (-, 60)

plasma grenade x8 (-, 15)
frag grenade x4 (-, 15)

Action shots:

I am very confident that you will enjoy this map. Please rate and post comments.

EDIT: thanks to lodex for coming up for the design for the control room AKA the lodex room :D