Cup of Athelstan

The Cup of Athelstan was a historical treasure stored in the International Gallery in London, worth 18 million pounds.

History
The cup was given to Athelstan, King of England, in 924 AD as a coronation gift from Hywel, King of the Welsh.

Lady Christina de Souza stole it during Easter 2009 and then travelled on a bus, The 200, through a wormhole to another planet. The Doctor later used it to get the bus and the passengers on-board the bus, back through the wormhole to Earth. Unfortunately, he had to destroy the cup in the process. (DW: Planet of the Dead)

After the Cup of Athelstan's disappearance, security was vastly improved for the Mona Lisa. (SJA: Mona Lisa's Revenge)