The best known ancient Greek pyramid is known as the Pyramid of Hellinikon . In the time of the geographer Pausanias it was considered to be a tomb.
The age of this structure is a matter of some controversy as various dating methodologies have provided conflicting results. But the most likely estimate is that it was built some time in the 4th century BC. However some archaeologists have argued that it dates as far back as the third millennium BC which would mean its construction corresponded with those in Egypt. This would provide some support for the mythological links supposed to have existed between Egypt and Argos.
As with other Greek pyramids the size of the one at Elliniko is considerably smaller than those in Egypt; the external base is just 7 metres by 9 metres. Another difference is that it did not have a pointed top. The walls slope at an angle of 60 degrees for 3.5 metres after which there was a flat surface. Internally there is a narrow corridor leading off the entrance at the South East side of the pyramid. This corridor provides access to the main interior room which is around 7 metres square.
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.