Ponte Vella is a medieval footbridge built on Roman foundations in Ourense. At one time, it was considered to be the biggest bridge in all of Spain.
The original bridge across the Minho River was built during the first century rule of Emperor Augustus though other sources state that it was built during the Trajan period. A mention is made of this bridge in the will of Doña Urraca, where it is said that it was repaired with funds provided by Ferdinand III. From the Middle Ages, it has provided access to the city of Ourense for trade and pilgrimage.
The structure was rebuilt in 1230 by Bishop Lorenzo on Roman foundations (original piers), and repaired in 1449 by Bishop Pedro de Silva. It then measured 402 m long, with an arch span of 48 m. However, the main arch collapsed in 1499 and the bridge was rebuilt in 1679 to a length of 370 metres with seven arched spans, the main span measuring 43 metres.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.