Harp of Rassilon
From Tardis Wiki, the free Doctor Who reference
The Harp of Rassilon was a key to a secret door in the High Council chambers. A painting beside the harp showed a music score for a piece of music known as "Rassilon's Lament". (NA: Blood Harvest)
By playing the music shown in the painting on the Harp, one could enter into a secret chamber which contained the Time Scoop controls once used illicitly by Borusa. (DW: The Five Doctors)
