Haven't visited any because the majority are private residences (although this one in Berkeley-ish has been on and off the market https://www.zillow.com/homedetails/700-Hillside-Ave-Albany-C... ). The only ones you can just go to are West Dean in the UK and Eishin just outside Tokyo (which IIRC you need an appointment for). I suppose there's also the Fresno farmer's market but that's barely a building.

(You may also be able to go to the Mexicali compound which is apparently still standing: https://maps.app.goo.gl/UkwKqYDrGBcfQLnd6 but don't know what the story is with it.)