St. Hans and St. Peter churches were built side by side during the 1200s. St. Peter was consecrated to the apostle Peter. St. Hans, which was the larger church, was dedicated to St. John the Evangelist. It was where the Lutheran doctrine for the first time preached on the island. In 1527, however, Bishop Brask turned Lutherans out from the church. But as soon as the bishop sailed to Denmark, Lutherans worships were started again. Churches were demolished in 1600-1800s and the stone was used among others to construct Lythbergska house. In 1982 a beautifully decorated gravestone was found in the ruins of in St. Hans, dating from 1050s.
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.