1505

1505 was a year.
The Twelfth Doctor and Clara Oswald visited Leonardo da Vinci in Florence, where Clara became the model for the painting later known as Mona Lisa. (COMIC: The Swords of Kali)
Around the same time, the Fourth Doctor arrived at Leonardo's studio from the year 1979, seeking clues to Count Scarlioni's plot to steal the Mona Lisa in that year. Leonardo, the Doctor discovered, was painting copies of his most famous work for his new patron, Captain Tancredi. He learned that Scarlioni and Tancredi were actually temporal splinters of the same person — Scaroth, last of the Jagaroth. After being briefly captured and interrogated by Tancredi, the Doctor escaped back to 1979, after writing, "This is a fake", on Leonardo's canvases in felt tip pen. 
During these events, the Doctor also saw one of Leonardo's early designs for a helicopter, and commented that the idea "took a bit longer to catch on". (TV: City of Death)