Ram Setu.

Adam's Bridge, also known as Rama's Bridge or Rama Setu, is a chain of natural limestone shoals, between Pamban Island, also known as Rameswaram Island, off the south-eastern coast of Tamil Nadu, India, and Mannar Island, off the north-western coast of Sri Lanka. 

In the Hindu epic Ramayana, Nala (Sanskrit: नल, IAST: nala, lit. lotus), is the vanara (monkey), who is credited as the engineer of the Rama Setu, a bridge across the ocean between Rameswaram (India) and Lanka, identified with modern-day Sri Lanka, so forces of the god Rama can pass over to Lanka.

The bridge starts as a chain of shoals from the Dhanushkodi tip of India's Pamban Island. It ends at Sri Lanka's Mannar Island. Pamban Island is accessed from the Indian mainland by the 2-km-long Pamban Bridge.

based on the Ram Setu. After the news of NASA imagery started doing the rounds, NASA made a statement saying that they never said Ram Setu is man-made, or 1.75 million years old. Delhi Science Forum wrote about how religious fundamentalists had fabricated these claims.

The bridge was reportedly passable on foot up to the 15th century until storms deepened the channel. Temple records suggest that Adam's Bridge or Ram Setu was completely above sea level till 1480 when it was broken by a cyclone that hit the area.

Lord Rama demolish a part of Ram Setu himself on the request of Vibhishan the new King of Lanka. When Lord Rama was leaving the Lanka on the way to Ayodhya Vibhishan requested to do so.