Altena Castle was erected by the brothers Adolf and Everhard von Berg around the year 1108 after Henry V granted them land in Sauerland. On Wulfseck Mountain they built their castle, which they named Wulfeshagen, later Altena. This is one of the three legends of the establishment of the county of Altena and the building of the castle.
After the acquisition of Mark near the city of Hamm in 1198, the counts of Altena took Mark Castle as their primary residence and called themselves the Counts of the Mark. They occasionally inhabited Altena Castle and from 1392 onward it was used as a residence for the county bailiff (Amtmann).
In 1912, Richard Schirrmann established the world's first youth hostel within the castle, which is still in use today (Jugendherberge Burg Altena).
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.