In our living room, we have 6 large windows. When Justin was about a year old, he decided to climb up into one of the windows.
Well, he ended up outside on the ground crying in the rain.
After that day, I was trying to think of something to put over the windows to protect him.
Than one day it came to me, gates.
So all the windows now have gates in front of them. This has worked, he does like to climb up on the ledge of the windows. He'll hold the top of the gates, and look out.