One of the most ancient temples in Kurukshetra, Sthaneshwar Mahadev is dedicated to Shiva and predates even the Mahabharata war according to tradition. The current structure was largely rebuilt in the 19th century but the site's sanctity is continuous — generations of pilgrims have come here specifically because the Pandavas prayed here before taking up arms. The tank beside the temple is calm and well kept; priests bathe in it before the morning rituals.
The temple is slightly removed from the main Brahma Sarovar circuit, a kilometre or so north of the tanks, which means it receives fewer casual visitors. Pujas are conducted throughout the day; the morning aarti at sunrise is particularly worth attending if you are staying nearby. The atmosphere is genuine and untheatrical — this is a working temple serving a local congregation as much as a pilgrimage crowd.