Le Trépied is a prehistoric passage grave built during the Neolithic period (4000 to 2500 BC). It is a single chamber tomb, 5.5 metres in length and two metres at its widest point with three capstones, one of which was returned to its original position in the 1870s after it had fallen off.
Excavations in 1840 discovered pottery and flint arrowheads dating to 1800BC showing that the site was still in use then. The tomb was repeatedly mentioned in the 17th century witch trials as a meeting place for witches and as the venue for the sabbats. One story says that the witches used to perform chants mocking the Virgin Mary whose shrine of Notre Dame de Lihou once stood on the nearby island which can be seen from the headland where the tomb stands.
References:The Clementinum is a historic complex of buildings in Prague. Until recently the complex hosted the National, University and Technical libraries, the City Library also being located nearby on Mariánské Náměstí. The Technical library and the Municipal library have moved to the Prague National Technical Library at Technická 6 since 2009. It is currently in use as the National Library of the Czech Republic.
Its history dates from the existence of a chapel dedicated to Saint Clement in the 11th century. A Dominican monastery was founded in the medieval period, which was transformed in 1556 to a Jesuit college. In 1622 the Jesuits transferred the library of Charles University to the Klementinum, and the college was merged with the University in 1654. The Jesuits remained until 1773, when the Klementinum was established as an observatory, library, and university by the Empress Maria Theresa of Austria.