Aeroexpress Floatplane Station
“The floatplane station of Aeroexpress Ltd. operated stood here from 1923 to 1926. Flights to Wien and Lake Balaton took off from the station. Its most famous pilot, our subsequent ocean flier, was György Endresz.”
The plaque is on Szabadság (Freedom) bridge in downtown Budapest, and of course you can see no floatplanes now. Only some ukranian-built hydrofoils traveling to Esztergom and Wien. But in the Fortepan.hu archive, you can find pictures of the planes: http://www.fortepan.hu/?img=16369 (Photo by Weygand Tibor)
Coordinates are: 47.484739803, 19.053412378