Jag Mandir is the famous Lake Garden Palace. It has a long history of being built. The palace was built by three Maha Ranas of Mewar Kingdom. It was started in 1551 by Maharana Amar Singh, continued by Maharana Karan Singh (1620–1628) and finally completed by Maharana Jagat Singh I (1628–1652). The palace gets the title after the last Maha Rana as "Jagat Mandir". The Garden palace was the summer resort for the Royal family and also venue for many royal parties.
The palace served as a shelter to refugees on two historic occasions. Maharana Karan Singh provided refugee to the Mughal prince Khurram (Emperor Shahjahan) during 1623 to 1624. There is a belief that this invite was extended as Prince Khurram’s mother was a Rajput Hindu lady. Prince Khurram rebelled against the Emperor for the Mughal throne. He took shelter in the City Palace initially and later was shifted to the Gul Mahal along with his wife and two sons. Again two centuries later Maharana Swaroop Singh provided refuge to many European families that fled during the 1857 Mutiny. The Jag Niwas palace was used as a refugee camp. In order to protect the refugees, all boats in the town were destroyed so that the rebels cannot reach the island.
Post Independence of India, Prince Bhupal Singh took the initiative of merging the Mewar kingdom with the Indian Union.