The Mona Lisa was stolen around 1911 and I believe it wasn't until 1913, the thief was caught. I'm positive the painting was missing for more than a couple months but if you try putting years into months, that would be 24 months.
Guillaume Apollinaire was arrested for stealing the Mona Lisa on Sept 07 1911
But this is not the first time it was stolen however... it was believed to be stolen also by the Nazis in a museum raid over 50 pounds of paintings were stolen along with the Mona Lisa even though the Mona Lisa has been recovered it has been vandalized many times with things such as coffee spray paint and knifes but it has been restored to its original condition
Fun fact: the Mona Lisa doesn't have eyebrows OR <span>eyelashes</span>