Here is the park website: Battlefield House Museum, and a map:
I've been inside the castle a few times, it is just a staircase that lets you climb to the top - and the look out deck. It's pretty neat.
This is the museum.
A door to wonderland? Probably not. I opened it, not too exciting, I think it is storage.
This is the old Jackson house. It used to be located at the corner of Nash and King, it was in a Cherry orchard. Sadly, the orchard was ripped out and town houses were built. The Jackson house was moved to this location. Read more about this here.
The house was closed up, but I did manage to peek my camera though the curtains to get this interior shot.
Lots and lots of flowers!
Battlefield Park is great for walking, hiking, and picnics. It is also often used for wedding pictures. I have walked around the park a million times, and I suggest that you plan a trip to Stoney Creek to see it too. It is free to park and explore the property, and there are fees and hours for museum tours.