I remember seeing Cecil Fielder hit a couple out of Tiger Stadium. Those inspired some feverish HRD between me and friends.
Glenalen Hill mashed one as a Cub that went over the rooftops across the street beyond the Wrigley bleachers.
That shot Bonds lifted off of Percival in the WS. Or Pujols unloading on Lidge in the NLCS. Those were colossal smashes.
I also don't believe for a second that Mantle hit one 565. The story changed a lot over the years and beyond that, it supposedly hit a sign 460 feet away - far as ****, but impossible to say for sure how far it went.
It seems to me that 515-520 is about the max a ball can go.