English villani, bordarii, cottarii, and servi on the land of the barons were subjugated into a condition of "villeinage" servitude and became "tied to the land" so that they could not leave the land without their lord's permission. The villeins formed a new bottom class as the population's percentage of slaves declined dramatically. They held their land of their lord, the baron. To guard against uprisings of the conquered people, the barons used villein labor to build about a hundred great stone castles, with moats and walls with towers around them, at easily defensible positions such as hilltops all over the nation. A castle could be built only with permission of the King. A typical castle had a stone building of about four floors on a small, steep hill. Later it also had an open area surrounded by a stone wall with towers at the corners. Around the wall were ditches and banks and perhaps a moat. One traveled over these via a drawbridge let down at the gatehouse of the enclosing wall. On either side of the gatehouse were chambers for the guards. Arrows could be shot through slits in the enclosing walls. Inside the enclosed area might be stables, a granary, barracks for the soldiers, and workshops. The castle building was entered by an outer wood staircase to the guard room on the second floor. The first floor had a well and was used as a storehouse and/or dungeons for prisoners. The second floor had a two-storied great hall, with small rooms and aisles around it within the thick walls. There was also a chapel area on the second floor. There were small areas of the third floor which could be used for sleeping. The floors were wood and were reached by a spiral stone staircase in one corner of the building. Sometimes there was a reservoir of water on an upper level with pipes carrying the water to floors below. Each floor had a fireplace with a slanted flue going through the wall to the outside. There were toilets in the walls with a pit or shaft down the exterior of the wall. The first floor had only arrow slits in the walls, but the higher floors had small windows.