From the Wikipedia page 
The Richard III Museum is located in the tallest of the four gatehouses, Monk Bar, in the historical city walls of York, England. It presents to visitors the life of Richard III, the last king of the Plantagenet dynasty.
Visitors to the museum are asked to consider the alleged guilt of King Richard for the murder of the Princes in the Tower. The facts of the case are presented, and it is made clear that much of the evidence against Richard is not contemporary, and that some was black propaganda encouraged by the Tudor dynasty. Visitors are then allowed to decide the verdict for themselves.
The museum contains a medieval execution chamber, a working portcullis, which visitors can operate, and what is said to be the world's smallest prison cell.
In 2014 the Jorvik Group, (which includes the Jorvik Viking Centre), took over the space within Monk Bar that housed the Richard III Museum, and created "The Richard III Experience at Monk Bar". They also replaced the contents of the Micklegate Bar Museum and created "The Henry VII Experience at Micklegate Bar".
The website is 
There are plans for a museum in Leicester.