Dun Ardtreck is a D-shaped dun, or 'semi-broch', situated on a rocky knoll on the edge of a cliff overlooking the sea. It encloses an area of about 13 by 10 metres. It was constructed with a ruidmentary hollow-wall. The entrance is particularly well-preserved with door-checks characteristic of brochs. The entrance to a guard cell led off to the right behind the door-checks.
Dun Ardtreck was excavated by Euan W. MacKie in 1964-1965 as part of an exercise to establish the development of the broch. It had been built in two stages: a roughly level platform was constructed and on this was set the galleried wall. Charcoal from the platform was radiocarbon dated to 115 BC. The first phase of occupation seems to have been very short and it appears to have ended in violence and destruction. The second phase was dated from the pottery finds to the middle of the 2nd century AD. The finds from this period included iron tools, bronze ornaments and glass ring-heads as well as Roman Samian ware pottery sherds and a piece of a Roman bead.
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.