In 2013, archaeological excavations in Egypt unearthed an interesting artifact. The flattened piece of limestone had a semicircle drawn onto it, which had been divided into 12 sections. In the middle of the stone was an indent that likely held a wood or metal bolt that would cast a shadow onto the design below. This device, found near a group of stone huts used in the 13th century BCE., is the oldest sundial on record.

In Ancient Egypt, small sundials like this were used as simple household timekeepers. Similar tools were created around the world and though they took on several different shapes and sizes, all used the movement of shadows to record the time. Many of these historic devices still stand and have been joined by modern takes on this ancient tool—some even taking the form of entire skyscrapers.

The world’s second-largest sundial is located in Jaipur, India, and is made entirely of stone. Designed during the 18th century, the Jantar Mantar astronomical observation site contains several instruments, including the Samrat Yantra, a 73-foot-tall sundial. Across the globe in Barnwell, South Carolina, you can find the only free-standing, vertical sundial in the United States. The timepiece has been standing since 1858 and is accurate within two minutes of standard time. From the world’s first digital sundial to a bridge that doubles as a timekeeper, here is a collection of our favorite sundials.