Koreshan State Historical Site.
The interesting thing about this religious based organization (cult) was their core belief. The Koreshans, as they were called, believed the earth was a hollow ball and we all live on the inside. Cyrus and his followers devised some pretty complex math and complicated measuring devices. They even took their equipment and calculations to Fort Myers Beach to prove their theories.
I applaud free thinkers and appreciate those of us who are willing to face ridicule in the following of their beliefs. It's pretty clear today they might have made the classic "forgot to carry the one" type of mistake in their math but this one theory was not all there was to the sect. They had some very interesting beliefs in social engineering and city master planning. Those might have taken hold even if the hollow earth theory lost out to science.
I found it fascinating they were early adopters of electricity. With Edison just up the road it's understandable. When they cranked up their first generator, the folks in Fort Myers thought electricity would harm the crops and dry up the cows. One hundred years later, those things would come true if electricity stopped flowing. The Koreshans actually supplied electricity to their neighbors until Florida Power and Light was established in the area.
One of the facts you won't find online is that when Cyrus died, he was put into a bath tub and his followers waited for him to rise from the dead until the Fort Myers health department ordered a burial. He was then put into a concrete coffin on the beach and was attended night and day by the faithful until a hurricane washed him out to sea. I'm still not judging but so far he has not returned. My feeling - he's not going to.