We drove to see this as I was curious what it was for... I still don't know. It is a long connection of roof and arches with an overall curved design. It was built in 1908 and originally had a fountain at its center (from what I read). The fountain was replaced with a memorial to John F. Kennedy in 1965. It is definitely worth going to see, located up on a hill with a scenic view over the landscape. Once you look over the rail and down the hill you see a lot of trash, trash and more trash. It looks like people have been coming here for a long time to dump their trash over the railing and down the hill. While we were there two park employees came to empty the trash cans, but apparently no one will ever pick up the huge amount of trash on the ground. Also we noticed at the far end of the Colonnade someone was sleeping in a sleeping bag. KC probably could do more to help the homeless.