The Oriel was a trans-dimensional art gallery which opened in the 37th century. It held the Mona Lisa and all the great artworks from Earth that survived World War V.
Cazkelf helped design the Oriel specifically to create a resonance matrix to funnel psychic energy so he could power his distress beacon and return home. He hypnotised the humanoid visitors at the gallery's grand opening, and sent his distress beacon by stealing their psychic energy to power it. The Ninth Doctor created a feedback loop, returning the stolen energy back to its owners, and took Cazkelf to his home planet when Cazkelf's people didn't respond to the distress signal. With his world destroyed and desolate, Cazkelf returned to Earth; the Doctor advising him to "delight and amaze" his public audience. (COMIC: Art Attack)