This was the place where the marvelous Ruud water heaters were produced. We take hot running water for granted today, but in this 1908 catalogue, the novelty is brought out in the “instructions” at the front of the book:

COMPLETE DIRECTIONS

Note carefully the instructions
for operating the Ruud
Water Heater

“TURN THE FAUCET”

You may add hot water in your home to the list of innovations for which Pittsburgh is responsible.