The Bute family became rich from exporting coal. The 3rd Marquess of the Bute family was reputed to be the richest man in the world. Much of the castle has been rebuild in a style he and his architect William Burges thought it looked liked in ages past.

From 2004 to 2006 there have been major renovation works to the Castle. In the summer of 2006 all scaffolding has been removed.

The only place where there is still work going on is the area where parts of roman walls have been uncovered.