who built it?
Gundulf, Bishop of Rochester
Rochester Castle
Between 1087 and 1089, Rufus asked Gundulf, Bishop of Rochester, to build a new stone castle at Rochester.
when was rochester castle built? UNANSWERABLE
wiki:12875602
Rochester Castle [SEP] Introduction
It was during this conflict that the castle first saw military action; the city and castle were besieged after Odo made Rochester a headquarters for the rebellion. After the garrison capitulated, this first castle was abandoned. Between 1087 and 1089, Rufus asked Gundulf, Bishop of Rochester, to build a new stone castle at Rochester. He established the current extent of the castle. Though much altered through the centuries, some parts of Gundulf's work survive. In 1127 King Henry I granted the castle to the Archbishop of Canterbury in perpetuity. William de Corbeil built the massive keep that still dominates the castle today.