This is a photo taken in Kilkenny, Ireland. It shows a laneway that passes through one of the circular rows of houses that acted as a fortification in the bad old days. These laneways permitted controlled access to the inner part o fthe city. Below is an expanded view of the mouth to the seeming tunnel that actually passes through the houses. http://etherlabs.net/m.werneburg/pics/images/ireland/20020314468_2.jpg