In 1958 a version of the integrated circuit was invented in Dallas by Jack Kilby of Texas Instruments; this event punctuated the Dallas area's development as a center for high-technology manufacturing (though the technology Mr. Kilby developed was soon usurped by a competing technology simultaneously developed in the "Silicon Valley" in California by engineers who would go on to form Intel Corporation). During the 1950s and 1960s, Dallas became the nation's third-largest technology center, with the growth of such companies as Ling-Temco-Vought (LTV Corporation) and Texas Instruments. In 1957, developers Trammell Crow and John M. Stemmons opened a Home Furnishings Mart, designed by Donald H. Speck, that grew into the Dallas Market Center, the largest wholesale trade complex in the world. The same year, the Dallas Memorial Auditorium (now the Kay Bailey Hutchison Convention Center) opened near Canton and Akard Streets in what is now the Convention Center District of downtown. On November 22, 1963, United States President John F. Kennedy was assassinated on Elm Street while his motorcade passed through Dealey Plaza in downtown Dallas. The upper two floors of the building from which Lee Harvey Oswald shot Kennedy, the Texas School Book Depository, have been converted into a historical museum covering the former president's life and accomplishments, Kennedy was declared legally dead at Parkland Memorial Hospital, 30 minutes after the shooting.