Fort de la Conchée is an island fortification constructed by Sebastien Vauban. In 1689 Vauban conducted an inspections of French coastal fortifications for King Louis XIV, who wished to strengthen and improve the country's defences. In 1693 whilst the fort was being constructed the English raided the town. They landed on Conchée where they slighted the works and captured those working on the fort.
Again in 1695 the English, with their Dutch allies, attacked the fortress. Though the fort was unfinished, ten guns had been installed, which permitted the French to repulse the attack. The battery then turned its guns on the main attacking fleet causing much damage to it. The fort was finally finished in 1705. The fortress was demilitarised in 1901.
During the Second World war the Germans used the abandoned fort for target practice. The Allies then attacked the fort during St Malo's liberation.
The fort covers almost the entire island. The fortress consists of a granite two-storey structure, with an upper terrace for the fort's armament.References:
The Petersberg Citadel is one of the largest extant early-modern citadels in Europe and covers the whole north-western part of the Erfurt city centre. It was built after 1665 on Petersberg hill and was in military use until 1963. It dates from a time when Erfurt was ruled by the Electors of Mainz and is a unique example of the European style of fortress construction. Beneath the citadel is an underground maze of passageways that can be visited on guided tours organised by Erfurt Tourist Office.
The citadel was originally built on the site of a medieval Benedictine Monastery and the earliest parts of the complex date from the 12th century. Erfurt has also been ruled by Sweden, Prussia, Napoleon, the German Empire, the Nazis, and post-World War II Soviet occupying forces, and it was part of the German Democratic Republic (East Germany). All of these regimes used Petersberg Citadel and had an influence on its development. The baroque fortress was in military use until 1963. Since German reunification in 1990, the citadel has undergone significant restoration and it is now open to the public as a historic site.