At http://archaeologynewsnetwork.blogspot.co.uk/2014/08/ani-ruins-reveal-hi… … we have some nice pictures of Ani, an ancient 5000 year old Armenian settlement. At a recent symposium historian Sezai Yazici said a lot of underground features had been found such as secret water channels, monk's cells, meditation rooms, corridors, tunnels with traps and corners designed to thwart intruders, and various other underground structures more difficult to tie down.
In the 6th to 8th centuries AD there was a monastery at Ani. Some of the tunnels are 500m long and lead to secret rooms and hidey holes. Monks lived under the ground and this, it should be remembered, was during the Islamic invasions – a little bit of a taste of what may have happened is now going on in Iraq and Syria. Fear must have driven them to build the tunnel system, a complex network of escape routes and deterrents to anybody that may have ventured down them with evil intent.