This photo, taken on July 24, 1975, was one of the last pictures of Jimmy Hoffa—the legendary union boss whose disappearance has baffled the FBI for 37 years. On the last day he was seen, Hoffa was set to meet with New Jersey Teamsters boss and Mafia member Anthony Provenzano and Detroit Mafia captain Anthony Giacalone at the Machus Red Fox Restaurant in Bloomfield, Michigan, but only he showed up. After that, he was never heard from again. This cold case has inspired endless speculation about what really happened to Hoffa on July 30. And the mystery has endured over the decades: investigators are currently looking into a "credible" tip that Hoffa's body lies under a home in Roseville, Michigan. Here's a look back at the places searched high and low for the long-missing Teamsters honcho.