Ram Sethu
The bridge was first mentioned in the ancient Indian Sanskrit epic Ramayana written by Valmiki, wherein Rama constructed it for his Vanara (ape men) army to reach Lanka and rescue his wife Sita from the Rakshasa king, Ravana.
Indian culture and religion includes legends that the structure is of supernatural origin.
According to the Hindu epic, Ramayana, Ravana, the ten-headed demon king of Lanka (Sri Lanka), enticed Rama's wife Sita with a magical golden deer, then kidnapped her and took her to Lanka, doing this for revenge against Rama and his brother Lakshmana for having cut off the nose of Ravana's sister, Shurpanakha.
To rescue Sita, Rama needed to cross to Lanka. Brahma created an army of vanara (intelligent warrior monkeys) to aid Rama. Led by Nila and under the engineering direction of Nala, the vanara constructed a bridge to Lanka in five days.
Rama crossed the sea on this bridge, and pursued Ravana for many days. He fired hundreds of golden arrows which became serpents that cut off Ravana's heads, but ultimately had to use the divine arrow of Brahma (which had the power of the gods in it and cannot miss its target) to slay Ravana.
This Bridge is also called as Adam's Bridge.