Space elevator

Real World Theory
A space elevator is a theoretical structure designed to transport material from a planet's surface into space. Many different types of space elevator structures have been proposed. They all share the goal of replacing rocket propulsion with the traversal of a fixed structure via a mechanism not unlike an elevator in order to move material into or beyond orbit. Space elevators have also sometimes been referred to as beanstalks, space bridges, space lifts, space ladders or orbital towers.

The most common proposal is a tether, usually in the form of a cable or ribbon, that spans from the surface to a point beyond geosynchronous orbit. As the planet rotates, the inertia at the end of the tether counteracts gravity and keeps the tether taut. Vehicles can then climb the tether and escape the planet's gravity without the use of rockets. Such a structure could eventually permit delivery of great quantities of cargo and people to orbit, and at costs only a fraction of those associated with current means.

In Halo
In Halo New Mombasa, a fictional metropolis, which figures prominently in the early levels of the video game Halo 2 has a Space Elevator. Set in 2552, it is a far-future version of present-day Mombasa, and is located in the fictional East African Protectorate (EAP) in what is now Kenya. The focal point of the city is it's space elevator, known as the Space Tether, near an artificial canal in the middle of the island-city.