ARTICLE AD BOX
Italy abolished its monarchy in 1947, but having no ruling power does not stop this annual gathering of the ex-royals. This year, all eyes are on Vittoria di Savoia, the first female heir to the Italian crown in a millennium.
The BBC's Katty Kay went to meet her.
Watch the full documentary Europe’s Royals Revealed with Katty Kay on BBC Select in the US and Canada and BBC iPlayer in the UK.