You can also head there in person and sign up for the tour at the Marlins Team Store when they are open. They are located next to the media entrance by Home Plate Plaza.
You can take a tour Monday Wednesday Friday and Saturday (check the times online.) Otherwise, no, you can't just walk in and check it out.
If its an event or venue sure. If its a tour call their guests services and see if it's offered.
Yes you can go without being a game
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