On April 10th, 1969, the second game of the 1969 World Series victory season, Mets center fielder Tommie Agee hit a HR into the upper left field deck at Shea Stadium in Flushing Meadows. No batter, before or since, reached the upper deck there. Tommie Agee passed away in 2001, The Expos played their last game at Shea Stadium in 2004, and Shea itself was demolished in 2009.
The “20” was Agee’s uniform number.