The château at Fontainebleau dates back to the 12th century, when the original building was commissioned by King Louis VII. Every subsequent ruler of France added to and expanded the château, with some of the most significant changes being commissioned by King François I, who is also credited for bringing Leonardo Da Vinci’s Gioconda to the Louvre.
The château de Fontainebleau is very different to Versailles, in that it was intended and mostly operated as the residence of the royals of France, whereas Versailles was never a home and only ever served as a showpiece for Louis XIV to enact his role as the roy soleil who ruled by divine prerogative.
Today, the château is open to the public. An adult ticket costs EUR13 and can be purchased either on location or online. Figuring there might be queues, I opted to get the ticket online. Although I needn’t have bothered because the place was far from crowded while I was there.
On the ground floor there is also a very nice café that serves an excellent lunch that I can highly recommend.
If you’re close to Paris and have a few days to spare, I can highly recommend a visit to Fontainebleau. I think it’s worthwhile to stay in the town of Fontainebleau for a few days, because it’s really quite charming. Also, the grounds of the château are mostly open to the public. Walking through the park in the evenings is lovely, with the golden light of the setting sun seeping in between the trees.
knightofmalta 
Well done William. It’s a good choice if Orly is your airport.
Actually I wondered. I could see aircraft at fairly low altitude. But I wasn’t sure if they were on their way to Orly or CDG.