Grave of Marie Laveau, the Voodoo Queen
New Orleans, Louisiana
According to local boosters this was, until recently, the second-most-visited grave in the U.S. (trailing only Elvis's in Graceland). Marie Laveau ran a New Orleans hairdressing salon during the day, but on her off-hours she was (supposedly) the Voodoo Queen, sought after for her potions and charms that would bring love or money to those willing to pay the price.
Laveau died in 1881, but a tradition later developed that she could still grant favors from beyond the grave if believers either left offerings or scrawled three X's on her tomb. This resulted in what was probably the most messy grave in the U.S., and caused no end of headaches for local preservationists, who had to constantly clean and repair the tomb only to have it trashed again.
They finally had enough, and on March 1, 2015, the cemetery was declared off-limits to all tourists except tour groups led by licensed tour guides.