Yesterday was the the appearance day of Lord Ramacandra as many of you know, and in that post we did yesterday taken from the Srimad Bhagavantam (1.3.22), Srila Prabhupada had this to say in his purport about the building of the bridge from India to Sri Lanka;
…Lord Rāmacandra prepared a royal road on the Indian Ocean with stones that floated on the water. The modern scientists have done research in the area of weightlessness, but it is not possible to bring in weightlessness anywhere and everywhere. But because weightlessness is the creation of the Lord by which He can make the gigantic planets fly and float in the air, He made the stones even within this earth to be weightless and prepared a stone bridge on the sea without any supporting pillar. That is the display of the power of God. (from purport SB 1.3.22)
The following is the scientific evidence from NASA supporting the story from the Ramamayana.
Ancient Bridge between India and Sri Lanka

Space images taken by NASA reveal a mysterious ancient bridge in the Palk Strait between India and Sri Lanka. The recently discovered bridge currently named as Adam’s Bridge is made of chain of shoals, c.18 mi (30 km) long.
The bridge’s unique curvature and composition by age reveals that it is man made. The legends as well as Archeological studies reveal that the first signs of human inhabitants in Sri Lanka date back to the a primitive age, about 1,750,000 years ago and the bridge’s age is also almost equivalent.
This information is a crucial aspect for an insight into the mysterious legend called Ramayana, which was supposed to have taken place in treta yuga (more than 1,700,000 years ago).
In this epic, there is a mentioning about a bridge, which was built between Rameshwaram (India) and Srilankan coast under the supervision of a dynamic and invincible figure called Rama who is supposed to be the incarnation of the supreme.
This information may not be of much importance to the archeologists who are interested in exploring the origins of man, but it is sure to open the spiritual gates of the people of the world to have come to know an ancient history linked to the Indian mythology.
[Courtesy: NASA Digital Image Collection] [Homepage: http://www.nasa.gov/%5D

Two more sources:
Sri Lanka History
The first signs of human inhabitants in Sri Lanka date back to the Stone Age, about 1.750.000 million years ago. These people are said to have come from the South of India and reached the Island through a land bridge connecting the Indian subcontinent to Sri Lanka named Adam’s Bridge. This is related so in the epic Hindu book of Ramayana.

Adam’s Bridge
Rama’s Bridge, chain of shoals, c.18 mi (30 km) long, in the Palk Strait between India and Sri Lanka. At high tide it is covered by c. 4 ft (1.2 m) of water. A steamer ferry links Rameswaram, India, with Mannar, Sri Lanka. According to Hindu legend, the bridge was built to transport Rama, hero of the Ramayana, to the island to rescue his wife Sita from the demon king Ravana.
Some text and images pasted from Krishna.org