Peregrine City 2018
June 29th 1985, a fleet of alien vessels appeared in high orbit over Earth. After several hours of panicked activity on the surface below, the bulk of the alien fleet abruptly vanished. It was quickly located, the city-sized mothership and its attending vessels having translocated to the Earth's surface in Antarctica. Shortly after, a shuttle departed the cityship on course for the UN where assembled world leaders and the people of Earth got their first look at the visitors.
The Vel-Jir who arrived at Earth are the last members of their species, fleeing the destruction of their realm. In exchange for Antarctica they offered to repair the world they would be sharing with humanity by patching the ozone layer, neutralizing global warming, and aiding in natural disaster relief. As the brief negotiations carried on it was politely but firmly made clear that whether or not the assembled humans accepted their help the aliens were taking the desolate, unused continent and that the three ships remaining in orbit were more than enough to protect their claim. In the face of this, the UN voted to accept their terms.
Since First Contact the Vel-Jir have met with humans cordially but rarely, keeping to mostly isolationist with regards to the humans sharing the planet with them.