On May 12, 2000 — Not only is Milwaukee’s 4-hour, 22-minute, 14 – 8 drubbing of Chicago the longest 9-inning game in National League history, it also features one of the longest home runs in the history of Wrigley Field. A picture circulated by the Associated Press puts it this way: “Rick Frohock celebrates on the rooftop of a three-story building on Waveland Ave. behind the left-field bleachers of Wrigley Field after catching a home run hit by Chicago’s Glenallen Hill against the Brewers. It was believed to be the first time a ball landed on top of the apartment building.” Hill’s shot is estimated at 490 feet by the next day’s press accounts and eventually measured at 500 feet.

Source:
Baseball Reference May 12