Many of us have explored, virtually at least, Krakow or Warsaw or other war-torn central European cities. I've found histories of the ETO and Ostfront during WWII to be helpful in urban T2K world-building. This article also has some food for thought.
http://gizmodo.com/what-happens-when...3/@laurendavis
Military theorists have been saying this for many years, but this piece has some interesting specifics and alternative takes on the nature of present and near-future MOUT.