This commemorative plaque says according to Google Translate:
1878 – 1955.
Double Olympic gold medalist and design engineer.
At the first Olympic Games in Athens in 1896, winner in the men’s 100 and 200 freestyle. At the 1924 Paris Olympics, silver medal winner in the stadium plan art competition.
Designer of the Hungarian National Swimming Pool.
Hungarian Olympic Committee.
(Image of HajÃ³s AlfrÃ©d is in the public domain according to Wikimedia Commons)