Leda and the Swan was a painting by the artist Leonardo da Vinci that was lost around three centuries before the year 2028. It was eventually owned by the siblings Penelope and Panos Polichroniadis, who kept it in their personal museum in 2028. When the Thirteenth Doctor came to the museum with Ryan Sinclair, Graham O'Brien and Yasmin Khan while tracking a Minoan statue of a Nimon, the Doctor found the painting among the Polichroniadis' collection. She was pleased to see it still in one piece and resolved to let Leonardo know. (PROSE: The Maze of Doom)