Archaeoastronomy is a field that studies how the ancients saw the stars – and how they used their knowledge of them. Ancient people in Egypt, Ireland, Greece, and the Americas were capable of determining the times of astronomical events with great accuracy, and incorporated this into their architecture. The Greeks used advanced knowledge of geometry to study the heavens, but even the Mayans, who had no written language, were able to gain advanced knowledge about the heavens and studied the movement of Venus.