Post copied from Bungie.net.. shortened a bit though
spent an hour a so writing this description.. don't feel like writing another.
Hope you guys like long descriptive posts! ;)

Link to map
Gametypes at very bottom
All links to screenshots are throughout the thread (for full size) and embedded images are at the bottom above gametypes
Perhaps I will have a video of me and a few others playing a game on this map as a demonstration up tomorrow on youtube as a demo, that is, if I can round up a couple people.

This map is 'finished', but, i am willing to change just about anything. All criticism/suggestions are appreciated!

Map Description-Two very asymmetrical bases with an alley down the center. Many passages and vantage points.
Works best with 6-12 players. Havn't tried 16, but this map does have support for 16.

Extra info-
There are two asymmetric bases, simply named Base 1 and Base 2, and a narrow alley down the center that connects the two. On both the left and the right of the alley, there are maze-like passages that are great for hiding or stealing the flag. The only other weapon other then the spawn weapons is a sniper. This is because a Battle Rifle + Magnum/SMG is all that is needed for balance. This map works VERY well for shotguns only, though. There are no grenades on the map, to cut down on grenade spam. Use your spawn 'nades wisely!

Detailed description of the bases
Base 1-
Inside view
General description-
Base 1 is very wide but short. The inside of Base 1 is very roomy. Inside Base 1, there are two 'rooms' and four Mongeese (Really just there for asthetics..) and a stairway two the roof.
On the roof of Base 1, there is a sniper that has 1 clip that respawns every 30 seconds, and many valuable places to go with it.
Tips for Base 1:
-Staying ontop of the roof and trying snipe isn't the best idea, but it works (screenshot - "Aerial view of Base 1")
-The semi-long narrow passage that has a cage at the end that is perfect for spying or sniping (screenshot - "Another place to go from Base 1")
-The small passage leads to the top of two boxes with small spaces between. Enemies will often try to take your flag this way. (screenshot - "One of many places to go from Base 1")
-There are many easily accesible (but not so visible) areas to get to, so explore a little
-Base 2 has a tripmine. It's a good idea to have one person go ahead of everyone else to either set it off or shoot it.
Base 1 changes In asymmetrical gametypes-
-There is a power drainer by the Mongeese
-The is a gravity lift by the mongeese

Base 2
Inside View
General Description
Base 2 is not so wide but it is tall. Inside Base 2, there is one tripmine, a little 'hiding' spot, and a staircase that leads to the roof.
On the roof of Base 2 are two snipers that respawn ever 45 seconds and have no clips (I did this so you can either share a sniper with a teammate or hog all the ammo).
Tips for Base 2
-The rooftop of Base 2 has an aerial view of two alleys (the center and the left). It is a great idea to stay up here and snipe (screenshots - "Base 2 is great for sniping" and "Sniping spot on Base 2")
-The open double box in front of base 2 is a great place to surprise an enemy from. It's a good idea to have a least one teammate here.
-Put the tripmine in a less visible but still usefull spot, and be sure to tell your teammates where! All to often someone will either A. throw the tripmine in a very visible area or B. throw it down and blow up a teammate (screenshot - "Inside of Base 2)
-Don't keep all your teammates on the roof! Everyone may want to snipe, but when you're playing CTF, that's not the best idea.
Base 2 changes in asymmetric gametypes-
-Two tripmines rather then one
-Two gravity lifts on the right side that lead to the roof that respawn every 30 seconds. If you see an enemy running at them, blow them up!

Detailed description of the center terrain
The center alley down the center is the main pathway to each base, but it is almost never a good idea to use it, because it's open and there are many places that you could be shot from. The alleyways off the left and the right are a safer alternative, but be careful, because with so many corners, an enemy could pop out at you at any time.
Tips for navagating the center terrain-
-The middle alley is almost never safe (screenshot - "Alleyway between the bases)
-Base 1 has an advantage over the left alleyway, sense they can easily reach the vantage points above it (screenshot - "One of many places to go from Base 1")
-Base 2 has an advantage over the right alleyway, sense they have an easy aerial view of it (screenshot - "Sniping spot on Base 2)

All the screenshots-
[img width=800 height=450]http://i31.photobucket.com/albums/c393/woozyj/Halo%203/17723122-Full.jpg

One of many ways to go from Base 1

[img width=800 height=450]http://i31.photobucket.com/albums/c393/woozyj/Halo%203/17723092-Full.jpg

Sniping spot on Base 2 -The left alley

[img width=800 height=450]http://i31.photobucket.com/albums/c393/woozyj/Halo%203/17723063-Full.jpg

Base 2 is great for sniping

[img width=800 height=450]http://i31.photobucket.com/albums/c393/woozyj/Halo%203/17723045-Full.jpg

Another place to go from Base 1

[img width=800 height=450]http://i31.photobucket.com/albums/c393/woozyj/Halo%203/17723018-Full.jpg

Where the flag of Base 1 resides

[img width=800 height=450]http://i31.photobucket.com/albums/c393/woozyj/Halo%203/17723017-Full.jpg

Aerial view of the Urban map

[img width=800 height=450]http://i31.photobucket.com/albums/c393/woozyj/Halo%203/17723016-Full.jpg

Alleyway between the bases

[img width=800 height=450]http://i31.photobucket.com/albums/c393/woozyj/Halo%203/17722974-Full.jpg

Where the flag of Base 2 resides

[img width=800 height=450]http://i31.photobucket.com/albums/c393/woozyj/Halo%203/17722972-Full.jpg

Inside of Base 1

[img width=800 height=450]http://i31.photobucket.com/albums/c393/woozyj/Halo%203/17722956-Full.jpg

Inside of Base 2

[img width=800 height=450]http://i31.photobucket.com/albums/c393/woozyj/Halo%203/17722955-Full.jpg

Aerial view of Base 1

[img width=800 height=450]http://i31.photobucket.com/albums/c393/woozyj/Halo%203/17722919-Full.jpg

Aerial view of Base 2

So far, Urbin only supports Slayer and One Flag (well, it has support for regular CTF if you take the one flag varient and set it to multiple flags, but, don't be surprised if there's glitches with it). If you guys like this map, I will add support for Assault, territories, and maybe even VIP.
Urban One Flag
Urbin Warfare (Slayer)
(Description of gametypes at threads)

Got any questions, suggestions, comments, bugs, etc.? Leave a reply!

Enjoy!

Noted suggestion - replace BR with AR or SMG.
Tell me what you guys think of this.