The fort at Coronado Heights serves as a picnic shelter and lookout point. Inside the ground floor of the fort is a single large and dark room. There is a very large stone table and stone benches. I'm not sure I would enjoy picnicking inside of the fort building as it is rather dark and dank.
Just inside the entrance to the fort is a very, very steep stone stairway leading to an upper deck that serves as an observation area. The stairs themselves are a bit nasty to climb, but if you enjoy looking out on the world, well worth the effort.
The last time we visited the fort we got a terrible scare because of the stairway. Our Siberian Husky went with us up to the top of the fort and for some reason decided to jump up on the stone barricade cordoning off the stairwell. He went up and over the barricade and down the entire height of the stairwell to the stone floor below. He let out a horrific yelp, we ran down the stairs after him, he got up, shook himself off and then acted as if nothing had happened. Anyway, the stairs at the fort are something to be careful of -- especially if you are a Siberian Husky dreaming that you are an acrobat.