Skyhook

A skyhook is an orbital elevator, tethering a planet at the equator to a geosynchronous orbital counterweight. Mars built the first skyhook in 2068, but since the game isn't called Red Planet, nobody cares.

The skyhooks that people do care about are the ones on Earth, as follows.

Port Horizon

Earth's first skyhook, simply called "the Skyhook" in older and GEO-aligned materials, stretches 38,000 kilometers from Port Horizon (a GEO-owned and -administered holding in what has since grown to be the Quito metropolitan area) on the surface to Clarke Station in orbit. It was built in 2071, and the Athena Project would never have launched without it.

Early in the Blight, unknown parties (presumed to be ecoterrorists) severed the Skyhook just outside Earth's breathable atmosphere, cutting off surface travel into space until 2135.

The COAP

Mombasa's Cooperative Orbital Access Project was opened in 2149, after almost a full decade of work by Atlas Materials, Biogene, Hanover Industries, MacLeod Enforcement, and the People's Republic of China.

The COAP is significant for two reasons above and beyond being a monumental construction task: its lifting weight and its jurisdiction. The Mombasa skyhook has move twice as much mass into orbit as Port Horizon, and its joint ownership by Incorporate city-states and the PRC mean that it's outside the GEO's jurisdiction and can (and does) approve people and cargoes for shipment that would never get past the GEO. Without the COAP, the Recontact-era colonization of Poseidon would playout very differently.