Ike Sewell and his business partner Richard Novaretti (better known as Ric Riccardo) opened a pizzeria at 29 East Ohio Street in 1943 and began serving the world's first deep-dish pizza.  Their new twist on a milennium-old dish was such an immense hit that they were unable to accommodate the demand, so in 1955 they opened a second restaurant at this location, about a block away.  They named the second restaurant "Pizzeria Due" and promptly changed the name of the first restaurant (then known as "Pizzeria Riccardo") to "Pizzeria Uno."