India

Jantar Mantar, built by King Jai Singh II between 1727 and 1734, literally means "calculation instrument". More than just a curious collection of sculptures, each structure at the intriguing Jantar Mantar observatory has a specialised astronomical function. There are 14 structures in total, which measure time, predict eclipses, and track stars. The most impressive one is the huge Samrat Yantra sundial. At a height of 90 feet (27 meters), it has a shadow that moves roughly the width of a person's hand every minute. It's profound display of how quickly time does in fact go!