The Ponts Couverts are a set of three bridges and four towers that make up a defensive work erected in the 13th century on the River Ill in the city of Strasbourg in France. The three bridges cross the four river channels of the River Ill that flow through Strasbourg's historic Petite France quarter. The Ponts Couverts have been classified as a Monument historique since 1928.
Construction of the Ponts Couverts commenced in 1230, and they were opened in 1250. As a defensive mechanism, they were superseded by the Barrage Vauban, just upstream, in 1690, but remained in use as bridges. As built, each of the bridges was covered by a wooden roof that served to protect the defenders who would have been stationed on them in time of war. These roofs were removed in 1784, but name Ponts Couverts (covered bridges) has remained in common use ever since.References:
First record of Kastelholma (or Kastelholm) castle is from the year 1388 in the contract of Queen Margaret I of Denmark, where a large portion of the inheritance of Bo Jonsson Grip was given to the queen. The heyday of the castle was in the 15th and 16th centuries when it was administrated by Danish and Swedish kings and stewards of the realms. Kastelhoma was expanded and enhanced several times.
In the end of 16th century castle was owned by the previous queen Catherine Jagellon (Stenbock), an enemy of the King of Sweden Eric XIV. King Eric conquered Kastelholma in 1599 and all defending officers were taken to Turku and executed. The castle was damaged under the siege and it took 30 years to renovate it.
In 1634 Åland was joined with the County of Åbo and Björneborg and Kastelholma lost its administrative status.