Europeans in the middle ages were great builders of churches and castles. There two classes of buildings expressed the ideas that ruled medieval life. The village might be and generally was, a collection of damp, dirty and droughty hovels, the city an insanitary huddle of houses, fit breeding place for plague, the castle primarily a fortress and secondarily a dark, cold inconvenient dwelling. But the church was built as well as decorated, as lavishly as local effort could manage. Its windows were of glass and its walls were painted with pictures in bright colours. Its spire or the tower pointing upwards, directed the gaze of villager and citizen away from an unsatisfactory condition of earthly life to a cloud-land of vision and fancy.  Why were the medieval cities fit places for breeding plague ?