Context : Rienzi vowing to obtain justice for the death of his young brother, slain in a skirmish between the Colonna and the Orsini factions (or simply, Rienzi) is a painting by William Holman Hunt, produced in 1849 and currently in a private collection. 
Question : What is the name of the place where Rienzi vowing to obtain justice for the death of his young brother, slain in a skirmish between the Colonna and the Orsini factions can be found?
private collection