Rameswaram means Lord of Rama (Rāma-īśvaram) in Sanskrit, an epithet of Shiva, the presiding deity of the Ramanathaswamy Temple. According to one of the versions of Ramayana, Rama, the seventh avatar of the god Vishnu, prayed to Shiva here to absolve any sins that he might have committed during his war against the demon-king Ravana in Sri Lanka. According to the Puranas (Hindu scriptures), upon the advice of sages, Rama along with his wife Sita and his brother Lakshmana, installed and worshipped the lingam (an iconic symbol of Shiva) here to expiate the sin of Brahmahatya incurred while killing of the Brahmin Ravana. To worship Shiva, Rama wanted to have a lingam and directed his trusted lieutenant Hanuman to bring it from Himalayas. Since it took longer to bring the lingam, Sita built a lingam, made of just Sands of the shores, which is also believed to be the one in the sanctum of the temple.Sethu Karai is a place 22 km before the island of Rameswaram from where Rama is believed to have built a floating stone bridge, the Ramsetu bridge, that further continued to Dhanushkodi in Rameswaram till Talaimannar in Sri Lanka. According to another version, as quoted in Adhyatma Ramayana, Rama installed the lingam before the construction of the bridge to Lanka. However, both Valmiki and KambaRamayana does not have any evidences about this Rameswaram story.(http://www.thehindu.com/opinion/letters/article2595588.ece)