Boppard’s most famous sight is a castrum, a Roman Fort. The military camp of Bodobrica was established here in 360 AD. It is thought to be the best preserved example north of the Alps today. It once had 28 towers, and was a commercial centre as well as a fort. It was 308 × 154 metres and formed a rectangle of 4,7 hectare. The walls were 3 metres thick to the land side and 2,5 metres thick to the Rhine side. With a height of 9 metres and 20 horse-shoe shaped towers to the land side, each 27 metres apart, the wall made a very powerful fortification.
The fort can be wandered around freely and it is in remarkably preserved condition. Many of the finds that have been recovered and excavated from the site can be found in the Boppard museum.References:
The city walls of Avila were built in the 11th century to protect the citizens from the Moors. They have been well maintained throughout the centuries and are now a major tourist attraction as well as a UNESCO World Heritage Site. Visitors can walk around about half of the length of the walls.
The layout of the city is an even quadrilateral with a perimeter of 2,516 m. Its walls, which consist in part of stones already used in earlier constructions, have an average thickness of 3 m. Access to the city is afforded by nine gates of different periods; twin 20 m high towers, linked by a semi-circular arch, flank the oldest ones, Puerta de San Vicente and Puerta del Alcázar.