If you just want to look at the big arena, you can simply walk in. You can also pretty much park…read moreright next to the entrance. It's not obvious you can do this because entrance-way appears to only be for cars (arm-gate), but you can use the same passageway to waltz right in. I paid to go into the museum because I thought I needed to in order to just see the actual grounds, however, that was not the case. I don't think the museum was that interesting so I thought it was a bit of a waste of time and money.
If you must check out this place, I recommend just parking near the entrance and then walking straight in for an interesting look at a historic place. Then you can read all you want about it online!