There are plenty of observatories all over the world, but the Jantar Mantar is considered to be one of the largest observatories ever built. Combining religion, science and art, the Jantar Mantar is the name given to a series of five, magnificent structures built in Jaipur, New Delhi, Ujjan, Varanasi and Mathura. Jaipur was the seat of Maharaja Jai Singh II during the 1720's and this is when this magnificent structure was built here. The Jantar Mantar in Jaipur is considered to be the largest of the five observatories and also houses the world's largest sundial. The Universe and the Cosmos have always been of interest to man, and it was this interest that compelled the Maharaja to build an astronomical observatory. The term 'Jantar Mantar' is derived from the Sanskrit terms 'Yantra' and 'Mantra' meaning 'instruments' and 'formula' respectively. The term 'Yantra' was replaced with 'Jantar' which means 'magical'. The Jantar Mantar houses various architectural and astrological instruments that have caught the interests of astronomers, historians and architects around the world.