First built in the 13th century, but thoroughly altered in the 15th century, Ampudia Castle has a square plan with a gothic central courtyard and 4 towers on each corner. Half of the castle complex is surrounded by a barbican defended by cylindrical towers.
It belonged to different owners such as Juan Alfonso de Alburquerque, Sancho de Rojas and Pedro Garcia Herrera (Marsical of Castille) among others.
In 1521 it was assaulted and occupied by the Comuneros (Castillan independentists who fought against Charles I of Spain) headed by the belicious bishop Acuna. It was later retaken for the Crown by the Duke of Lerma.
Today Ampudia Castle is a private property, but its grounded departments can be visited on a guided tour. Other parts of the castle like the upper levels or the keep are not open for visit.
References:Kristiansten Fortress was built to protect the city against attack from the east. Construction was finished in 1685. General Johan Caspar von Cicignon, who was chief inspector of kuks fortifications, was responsible for the new town plan of Trondheim after the great fire of 18 April 1681. He also made the plans for the construction of Kristiansten Fortress.
The fortress was built during the period from 1682 to 1684 and strengthened to a complete defence fortification in 1691 by building an advanced post Kristiandsands bastion in the east and in 1695 with the now vanished Møllenberg skanse by the river Nidelven. These fortifications were encircled by a continuous palisade and thereby connected to the fortified city. In 1750 the fortress was modernized with new bastions and casemates to protect against mortar artillery.