Martinsburg Castle with its powerful hexagonal tower was built around 1324 as a toll station on the Rhine bank in Oberlahnstein. It was a toll castle in the Electorate of Mainz. The pictorial assembly was built together with the town fortification.
The pointed gate in the east wall shows a delicate cast iron oriel with emblem (1395). The north wing probably contained the main rooms. The apartment tower in the northwest, built in the 14th century, was modified in the 18th century. The south wing is likewise Gothic. The archbishop Franz Lothar von Schönborn established the southwest and west wing between 1719 and 1721; there the main tower (end of the 14th century) is assembled; at its windows one sees outside small console stones for the fold-down wooden shutters. The roof dates from the 18th century.
References:The Chapel of St. Martin is the only completely preserved Romanesque building in Vyšehrad and one of the oldest in Prague. In was built around 1100 in the eastern part of the fortified outer ward. Between 1100 and 1300, the Rotrunda was surrounded by a cemetery. The building survived the Hussite Wars and was used as the municipal prison of the Town of the Vyšehrad Hill.
During the Thirty Years’ War, it was used as gunpowder storage, from 1700 to 1750, it was renovated and reconsecrated. In 1784, the chapel was closed passed to the military management which kept using it as a warehouseand a cannon-amunition manufacturing facility. In 1841, it was meant to be demolished to give way to the construction of a new road through Vyšehrad. Eventually, only the original western entrance was walled up and replaced with a new one in the sountren side. The dilapidating Rotunda subsequently served as a shelter for the poor.