The basilica of St. Plechelm is a Roman Catholic church dedicated to the 8th-century Irish monk Saint Plechelm, whose festival on 15 July has been on the calendar of the medieval diocese of Utrecht ever since his canonisation in the 10th century.
The oldest parts of the existing building date from the middle and the second half of the 12th century, but the history of the church goes back to the 8th century, when the traveling missionary Plechelmus founded the first church on the site, the Silvesterkerk, initially dedicated to pope Silvester and sometime before 954 rededicated to Plechelmus himself (canonised after the elevation of his relics).
In 954, bishop Balderik of Utrecht founded a chapter in Oldenzaal and expanded and restored the 8th-century church, allowing the relics of Plechelmus used on his canonisation to be transferred to it. The current tower was erected around 1240. The church was enlarged in Gothic style in 1480s.
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.