Despite all the pretty much identical copies around, someone once just had to have the real Mona Lisa. Leonardo da Vinci’s famous painting vanished from the walls of the Salon Carré in the Louvre Museum on August 21st, 1911 – and it actually took a while for anyone to notice! A visiting artist, Louis Béroud, did alert guards to the fact that there were only empty pegs sitting between Correggio’s Mystical Marriage and Titian’s Allegory of Alfonso d’Avalos, but the guards told him the missing painting had probably just been taken away to be photographed or something. But when Béroud checked this out with higher authorities, it was discovered that the Mona Lisa was no longer part of the museum’s inventory.
About sixty police investigators descended on the Louvre and the place was closed for a week, but aside from a plate of glass and an empty frame being found on a staircase, no leads were forthcoming. Oh, there was a fingerprint, on the frame, but it didn’t match anything the police had in their files, so that didn’t help much.
Nothing helped much, and the Mona Lisa’s whereabouts remained unknown for two whole years. (It went on drawing the crowds for a while, though, because people were willing to stand in line to look at where it had been.)
Then, in November, 1913, an Italian antiques dealer named Alfredo Geri got a letter from someone who claimed to have the stolen painting. Geri contacted the museum director of the Uffizi Museum in Florence (Commendatore Giovanni Poggi) , who advised him to set up a meeting. The meeting was scheduled for December 22nd, but on December 10th, an Italian man calling himself Leonardo Vincenzo showed up at Geri’s office and told him the Mona Lisa was back in his hotel room and Geri could have it for a half million lire. He said the money was just to cover his expenses as his real motive for stealing the paining had been to restore the great art treasure to Italy, where it belonged. He then agreed to meet Geri and Poggi in his hotel room the next day so Poggi could check the painting’s authenticity.
When Geri and Poggi went to the hotel room, they found the man, whose real name was Vincenzo Peruggia, did indeed have the Mona Lisa hidden under the false bottom of a wooden trunk. Accepting Poggi’s statement that he’d have to compare it to other da Vinci paintings, Peruggia let the museum director take it away, and the police, who had been waiting in the wings, moved in and arrested him.
The Mona Lisa was returned to France on December 30th, but was first displayed throughout Italy – where many Italians thought it should have stayed.
Time Travelling With Kids 
There’s an ancient 1-season TV show I watch on Amazon Prime called “Voyagers.” It was based on historical events with two time travelers dropping (literally) in on times when history had to be tweaked to make it go right. At the end, they always said “If you want to learn more about….visit your local library.”
It had the Mona Lisa story in one of the episodes. I wish you could see the single season shows. I’m sure you’d enjoy them. It didn’t go any further because the main character was accidentally killed on the set of another series he was in. Guy’s name was Jon-Erik Hexum. I really felt bad when I saw he’d accidentally died at 26. What a waste. He was funny and very easy on the eyes. Anyway, maybe you can find Voyagers somewhere to watch. It was filmed in the early 1980s.
i also used to watch Voyageurs.
Very few people in this world can compete with Leonardo da Vinci for the title of The Supreme Genius of all ages. He is a true polymath and is regarded as a renaissance man. Read more about him here http://kaboomed.wordpress.com/2014/08/21/awesome-minds-leonardo-da-vinci/