Under Gallery as it was styled in the novelisation.
Talk about it here.
The Under-Gallery was situated beneath the National Gallery in London and was established by Elizabeth I to house dangerous art. Around the 2010s, 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)