Let us collect and highlight the life and science of Ancient India in the form of 'Did You Know?' snippets. Readers may add interesting snippets to this collection. No digressions or spam, please.

Transportation
Rig Veda, the oldest document of the human race includes references to the following modes of transportation:

Jalayan - a vehicle designed to operate in air and water.(6.58.3)
Kaara - a vehicle that operates on ground and in water.(9.14.1)
Tritala - a vehicle consisting of three stories. (3.14.1)
Trichakra Ratha - a three-wheeled vehicle designed to operate in the air.(4.36.1)
Vaayu Ratha - a gas or wind-powered chariot. (5.41.6)
Vidyut Ratha - a vehicle that operates on power.(3.14.1)

Irrigation
The world's oldest dam still in use is the Grand Anaicut or Kallanai, in Tamilnadu, which was built in the second century by the Chola king Karikalan.

Nuclear Bomb
The description in Mahabarata of the devastations caused by the brahmAstra, closely resembles the explosion of an atomic bomb. This is why Dr. Robert Oppenheimer (1904-1967), said to a query if the atomic bomb exploded in Alamogordo under the Manhattan Project, "Well -- yes. In modern times, of course."

Law of Gravity
The ancient Hindu astronomer Bhaskaracharya, states in the Surya Siddanta dated 400-500 C.E.:

"Objects fall on the earth due to a force of attraction by the earth. Therefore, the earth, planets, constellation, moon, and sun are held in orbit due to this force."

About 1200 years later Newton rediscovered this phenomenon, calling it the Law of Gravity!