So far that still exist 10, they are:
Fenway
Citi Field (Mets)
Citizens Bank (Phillies)
Wrigley (Cubs)
Camden Yards (Orioles)
Nationals Park (nationals obviously lol)
PNC (Pirates)
Minute Maid (Astros)
Progressive Field (Guardians)
Great American Ballpark (Reds)
I’ll be up to 15 at end of the season as I’m doing White Sox, Cubs (already seen but my roommate really wants to go and I’m down), Twins, Brewers and Cardinals and I have a die hard Yankees fan buddy who for his 30th birthday wants us to come to New York for a Yankees/Sox game, so that’s also loosely planned.
for stadiums that not longer exist. I saw nationals play at RFK stadium (it actually might still exist lol but it’s a shithole) and I went to old yankee stadium as a very young kid with my dad. I don’t have much memory of it.