I love Central Park, not because I've been there more than driving past it but I love how NYC designed this park and what they wanted and planned it for. I've seen it from across the street and I've been at it at the Tavern on the Green Restaurant. However, I've never had the time to thoroughly enjoy the park, perhaps some day I will.
Here is a link to a book published in 1869 about the park titled A Description of the New York Central Park it has great illustrations and I think you will enjoy it as well.
Here's a pic of the Belvedere Castle which was known simply as the Belvedere back then.