The Koppelpoort is a medieval gate in Amersfoort. The gate was built between 1380 and 1425 as part of the second city wall. The whole wall was completed around 1450. The gate was attacked in 1427 during the siege of the city, but this attack was repelled.
The gate was opened and closed every day by the appointed 'wheel-turners'. A minimum of twelve wheel-turners were collected morning and evening by several guards. It was an extremely dangerous task; if they did not begin walking simultaneously, then one could fall, dragging the rest along with often fatal results. Before the gate could come down, it had to be raised, to pull out the iron pins that held it in place. Only then could it come down. While the gate was going down, walking in the wheel grew ever easier and faster, and many people stumbled and broke their limbs. The koppelpoort was also never breached.
The Koppelpoort was given its current appearance during the restoration by Pierre Cuypers in 1885 and 1886. Among other things, Cuypers removed a step between the two gates and replaced it with a slope.
The latest restoration was completed in 1996. It was carried out very cautiously, and with respect for the old building materials.References:
Ängsö Castle was first named as "Engsev" in a royal charter by king Canute I of Sweden (r. 1167-1196), in which he stated that he had inherited the property after his father Eric IX of Sweden. Until 1272, it was owned by the Riseberga Abbey, and then taken over by Gregers Birgersson.
From 1475 until 1710, it was owned by the Sparre family. The current castle was built as a fortress by riksråd Bengt Fadersson Sparre in the 1480s. In 1522, Ängsö Castle was taken after a siege by king Gustav Vasa, since its owner, Fadersson's son Knut Bengtsson, sided with Christian II of Denmark. However, in 1538 it was given by the king to Bengtsson's daughter Hillevi Knutsdotter, who was married to Arvid Trolle.
In 1710, the castle was taken over by Carl Piper and Christina Piper. Ängsö Castle was owned by the Piper family from 1710 until 1971, and is now owned by the Westmanna foundation. The castle building itself was made into a museum in 1959 and was made a listed building in 1965. It is currently opened to visitors during the summers.
The castle is a cubical building in four stores made by stone and bricks. The lower parts is preserved from the middle ages. It was redecorated and expanded in the 1630s. The 4th storey as well as the roof is from the expansion of Carl Hårleman from 1740-41. It gained its current appearance in the 1740s.