Two weeks ago my company spent a week in an old abandoned British Military fortress learning the finer points of urban warfare.
We started out working individually, learning how to approach a room and make sure that you aren't exposed while simultaneously being able to see every angle in the room. In the beginning it feels a little unnatural, but after spending a few hours making sure that your leg, or shoulder aren't exposed you start to get the feel for it. In the future we are going to practice with paintball guns. It is a safe way to learn not to expose yourself. After a few paintballs to the leg from close range you learn quickly to make sure your body is concealed.
After that we moved on to pairs and groups of three. We learned how to approach narrow door frames, wide door frames, open stairwells (in which someone on the second floor could see you), and closed stairwells. As well as various techniques for entering these places. By the end of the week we had worked our way up to various groups of six searching a house for terrorists. In addition to the techniques we learned for entering, we also learned various tactics for entering a room when you are being attacked. For example, how to throw a grenade in, what to do if your gun jams, and how back someone up.
During the week we also advanced significantly in our close-combat training. We had two lessons a day all week. In which we learned how to defend ourselves against an attacker armed with a knife.
