Ram Sethu

In the Ramayana, Maharshi Valmiki has described about the Ram Sethu in details:–

“Samudram kshyovaya masunirpatanth samantath Sutranyanye pragrunhanti hyayatam sata yojanam”
Meaning: This great Sethu was constructed by the great builder Nala. On the first day, 14 yojan, on second day, 20 yojan, on third day, 21 yojan, on fourth day 22 yojan, on fifth day, 23 yojan and in toto 100 yojan-long Sethu was built.
Ref: Ramayan, Yuddha Kanda 22: 62

The Skandha Puran says, after returning from Lanka, Lord Ramachandra requested all the kings to protect and preserve this sacred Sethu.

“Bhuyo bhuyo vabino bhumipalah natwa natwa yachaye Ramachandra Samanwyo dharma sethu naranam kale kale palaniyo bhabidhi”
(Ref: 40:34)