An astronomical observatory from the time of the Thracians

This observatory, discovered near Staro Zhelezare, is the only one of its kind ever discovered on Bulgarian territory. The observatory is of the “Stonehenge” type and dates from the 6th century BC. The ancient Thracians built the observatory so that they could establish the exact solar equinox. They did this enormous work because the Sun was the main deity of the ancient Thracian peoples.