Stonebridge has the control point on a covered bridge in the middle of a map, spanning a shallow ditch. There are underground passages on either side of the map that give classes that work behind the frontlines a safe way to get around, and a relatively flat and empty area above that makes for great bases for 
engineers and a good spot for snipers. To assist in getting to the bridge there is also a set of pillars that can be crouch-jumped up by the faster classes. The bridge itself provides a lot of cover and is relatively easy to defend, making it harder for the attackers to push in. 

engineer bots get very confused, if they spawn in the bigger part of the spawn 

room they'll run around in place. Otherwise they set up sentries is a fairly 

intelligent location, which was surprising. Still though, this can lead to 

imbalances when you have two bots on your team taking up space, I don't know how 

to fix this behavior.