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 Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.