Anglo-Saxon monasticism developed the unusual institution of the "double monastery", a house of monks and a house of nuns, living next to each other, sharing a church but never mixing, and living separate lives of celibacy. These double monasteries were presided over by abbesses, who became some of the most powerful and influential women in Europe. Double monasteries which were built on strategic sites near rivers and coasts, accumulated immense wealth and power over multiple generations (their inheritances were not divided) and became centers of art and learning.