The Roman city of Cáparra is located in the valley of the River Alagón. In Roman times it was in the province of Lusitania within the Conventus Iuridicus Emeritensis, whose capital was Colonia Augusta Emerita (modern day Mérida). It was approached via the Roman road known as the Vía de la Plata and is now permanently abandoned.
Its excellent location led to Roman settlement achieving the category of municipium under Vespasian, around the year AD 74. From that point on, Cáparra really began to develop as a city. Its decline took place during the High Middle Ages, when it began to lose its population, becoming even more depopulated after the Moorish invasion.
The most representative element of this ancient Roman city is its tetrapylon or quadrifons arch, i.e. a four-gate arch. This arch was found in the centre of the city, crossed by the Roman Silver Route.
The tetrapylon arch has large ashlar foundations with a dressed stone finish, while the capitals finish in a cornice supporting an archivolt that in turn supports the groin vault. This arch is the only one of its kind in the Iberian Peninsula.
The Roman bridge of Cáparra is part of the monumental site of Cáparra. The work is not established in time and consists of four arches, of which only the central two can be considered fully Roman.
The arches are rounded and the vaults come out from a projecting course. Upriver, one of the cutwaters of the piles in the river’s course is triangular and the other trapezoidal, while the downstream face is flat. The work is clad in granite masonry arranged in somewhat irregular rows.
References:Ehrenbreitstein Fortress was built as the backbone of the regional fortification system, Festung Koblenz, by Prussia between 1817 and 1832 and guarded the middle Rhine region, an area that had been invaded by French troops repeatedly before. The fortress was never attacked.
Early fortifications at the site can be dated back to about 1000 BC. At about AD 1000 Ehrenbert erected a castle. The Archbishops of Trier expanded it with a supporting castle Burg Helferstein and guarded the Holy Tunic in it from 1657 to 1794. Successive Archbishops used the castle's strategic importance to barter between contending powers; thus in 1672 at the outset of war between France and Germany the Archbishop refused requests both from the envoys of Louis XIV and from Brandenburg's Ambassador, Christoph Caspar von Blumenthal, to permit the passage of troops across the Rhine.