The Mouse Tower (Mäuseturm) is a stone tower on a small island in the Rhine. The Romans were the first to build a structure on this site. It later became part of Franconia, and it fell and had to be rebuilt many times. Hatto II, the Archbishop of Mainz, restored the tower in 968. The story of how it came to be called the 'Mouse Tower' comes from a folk tale (Hatto was being eaten alive by mice in a tower). In 1298 the structure became an official customs collection tower. It was destroyed by a French army in 1689, then rebuilt in 1855 as a Prussian signal tower.
References:The Citadelle of Quebec is an active military installation and official residence of both the Canadian monarch and the Governor General of Canada. It is located atop Cap Diamant, adjoining the Plains of Abraham in Quebec City. The citadel is the oldest military building in Canada, and forms part of the fortifications of Quebec City, which is one of only two cities in North America still surrounded by fortifications, the other being Campeche, Mexico.
The first fortifications in Quebec were built by the Governor General of New France Louis de Buade, and completed just in time for the Battle of Quebec in 1690.
After the British conquest in the second half of the 18th century, the problem of Quebec City's defences grew more acute.