22km north of Udaipur and only open during specific darshan windows (check before you go - arriving between windows means a locked gate), so this only works if your day trip is timed around temple hours, not general sightseeing hours.
Tradition holds that the original shrine was built around 734 CE by Bappa Rawal, founder of the Guhila (later Sisodia) dynasty that would go on to rule Mewar, after he received the blessing of the sage Harit Rashi and the deity Eklingji, a form of Shiva. The 15th-century Sanskrit text Eklinga Mahatmya recounts this founding legend, and the shrine subsequently served as the tutelary temple of the Mewar royal house, whose rulers styled themselves as regents of Eklingji. The temple was damaged during Delhi Sultanate-era invasions and rebuilt across several phases by Maharanas Hamir Singh, Kumbha, and Raimal, with the standing marble-and-granite structure dating largely to a 15th-century restoration.