The Under Gallery was a gallery established by Elizabeth I to house dangerous art.
History
Queen Elizabeth I founded the Under Gallery in 1562 (AUDIO: The Curator's Gambit) to store art too dangerous for public consumption. (TV: The Day of the Doctor) It was located beneath Hampton Court Palace until it was relocated by Queen Victoria beneath the newly-built National Gallery in the 1830s. (AUDIO: The Curator's Gambit)
The entrance went unnoticed to the general public; the Curator remarked that not everyone could see it at all and few were invited. (AUDIO: Lost Property)
In 2013, the Eleventh Doctor and Clara Oswald were summoned there by UNIT to investigate a disturbance concerning broken Time Lord paintings. Upon arrival the Doctor discovered he had been made curator by the Queen, and that it was her wish that he be summoned should there be any disturbance there. It was later discovered that a group of Zygons had infiltrated the Under-Gallery by breaking out of the paintings, in reality Time Lord stasis cubes. Before the Doctor left, he met the acting curator of the Under-Gallery. (TV: The Day of the Doctor)
In 2014 or 2015, Kate Stewart called the Curator and arranged to have the arch moved to the Under Gallery to keep it from the Eleven. (AUDIO: Eleven's Eleven) The Curator agreed. (AUDIO: The Curator's Gambit)
In 2020, the Curator led Helen Sinclair into the Under Gallery knowing she would follow. He asked her to take care of the Eighth Doctor and warned her to expect danger on the horizon. (AUDIO: Lost Property) A few months later, Liv Chenka and Tania Bell sought his help to manage the physical effects of Tania's changing memories. He took them inside the Under Gallery and showed them The Untempered Vista, an artistic representation of the Untempered Schism which Tania's pain was stopped by looking at. The trio were chased into a tunnel by a physical representation of the Void, escaping through a door unlocked by the Curator into the train Robin and Ken Bright-Thompson had taken to Edinburgh a few months earlier. (AUDIO: Crossed Lines)