This woman stole my idea! Hahaha! Actually, I did exactly the same project last week, but I did not have the good idea to take a picture to share it with you, so I'll share hers.
Just like this lady, I had a spare door in the house, because I replaced my bedroom door to put an old barn door (really beautiful!). My old door was solid and very pretty, see:

I needed to use it to decorate my house!
I sanded it and I gave it a vintage finish.
Then, I fixed hooks on one of the longest sides of the door (the side where there is the hole of the handle).
I then glued my best pictures into each glass rectangle.

I hung the door in my hall and it's just beautiful!

You can also make a decorative frame if you do not want to put it in the entrance.

It's beautiful, is not it ?!
Source: photogmommie · Photo Credit: Capture image via photogmommie