Space elevator

The space elevator is a proposed launch assist system in the form of a long tether spanning from Earth's surface to the geostationary orbit.

Concept
Structures on the equator have tangential speed of around 450 m/s because of the Earth's rotation. If a tower with the height of 36000 km was built there, tangential speed of its peak would be over 3000 m/s, around the same as the orbital speed at that altitude. This means that objects released from that tower would be on orbit without having to use rockets for propulsion.