It would have to be one of the 1900's probably Harry Crebs first fight with Gene Tunney or Terry McGoverns second fight with Young Corbett.

Tough choice either that or back further into the no gloves days.

Outdoors in an open arena when they fought shorter rounds but up to a hundred minutes of fighting or more.You couldnt book a hotel room for 20 miles around any of those fights back then,they were so popular.
Can you imagine the aptmosphere! Standing there ringside in the bare dirt getting your pockets picked by cheap women in between side bets .