You can walk through the Garden on your own, but for the house itself you have to buy the tour. The same price gets you to all three museums within one week.
All tours through the Owens-Thomas House & Slave Quarters are guided. They leave everry 15-20 minutes with the last tour at 4:20. Afternoon tours can fill up and it is recommended that you get your spot early in the day.
Better to get a guided tour so you understand how things went on in the house
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