Delirium Archive
The Delirium Archive was a museum which took up most or all of an asteroid, and was the final resting place of the Headless Monks. The Doctor said it was "the biggest museum ever". It was implied he visited often, and used it to "keep score".
River Song deduced that eventually, the Doctor would at some point end up at the Delirium Archive and find the Home Box of the 51st century Category 4 Starliner "Byzantium". She left a graffiti message in Old High Gallifreyan on it, alerting him to her needing his help. He eventually did, roughly 12,000 years later. (DW: The Time of Angels)
The Museum held Magnatine Dynasty crystals, which, according to the Doctor, were "so beautiful they'll make your hair go curly with delight, or maybe with boredom". (NSA: The Forgotten Army)
