Ike Sewell (an All-Southwestern Conference guard for the University of Texas football team in 1924) and his italian-born business partner Richard novaretti (otherwise known as ric riccardo) created the world's first deep dish pizza at this location in 1943, although some sources report that the concept was actually developed by their chef, Rudy Malnati.  the restaurant was originally known as "the pizzeria" and then became "pizzeria riccardo."  the deep dish pizza was so popular that in 1955 they opened a second pizzeria a block away at 619 N. Wabash, where it (too) remains today.  the second restaurant was named "pizzeria due," and, upon its opening, the original restaurant at this location was renamed "pizzeria uno."  Today, Pizzeria Uno is a national chain, but old school Chicagoans know that it was born at this very location.  (Incidentally, the guy who typically gets the credit for starting it all, Ike Sewell, died of leukemia in 1990 at age 87.)