Built on the site of the Norman fortification known as Baynard's Castle which was demolished in 1213. Blackfriars Priory was initially a house and church for the Dominican Order (guess what colour their habits were). It expanded to occupy all the ground between Ludgate and the river with a refectory, cloisters, a hall, library, stables and garden. 1529 the location for the (failed) divorce hearing between Catherine of Aragon and Henry VIII. Closed in 1538 during the dissolution of the monasteries. One section of wall remains.
Lost City of London has a 3D drawing showing what the Blackfriars estate might have looked like.