The first sundials were built by the Egyptians and the Babylonians. These sundials date as far back as 5,000 BC. However, the first evidently purpose-built sundial was not constructed until 800 BC.
The obelisks built by the Egyptians and the Babylonians served more than their decorative purpose. They used the position of the shadow to estimate what time of day it was. However, the first actual sundial was discovered to have been constructed in 800 BC by the Egyptians. These early sundials were typically built from a green schist and were inscribed with six different time divisions. The direction of the shadow gives an approximation of what time it was.