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:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.