Alfava Metraxis

Alfava Metraxis was a planet which was orginally home to the Aplan, but in the far future was terraformed and colonised by Human settlers.

A notable landmark left on the planet by the Aplan were the Mazes of the Dead. These were large subterranean tombs complexes, adorned with statues of the dead. The Mazes have six levels, to represent the ascent of the soul.

The temple was originaly believed to a tomb of the Aplan who had mysteriously vanished centuries before however the truth was far more disturbing. It was actually the home of a large colony of Angels that had long ago exhausted their food supply and were too weak to attack a nearby human settlement on the planet.

By the 51st century, a lone fully powered Angel apprently allowed itself to be captured by pretending to be in a dormant cycle and waited until it was placed on a ship with a temporal core and when close to the planet crashed it on top of the temple. It used its powers to make sure the core didn't explode and directed the energy so it could recharge its brethren.

When the Byzantium crash landed there the Doctor, Amy Pond and River Song went to the temple there to investigate and save the people on the Byzantium. (DW: The Time of Angels)