In 1954 a young architect named I.M. Pei stood before city officials and media to unveil his plans for Denver’s first high-rise hotel complex. Pei, who would become one of the world’s preeminent architects, pledged that no expense would be spared in order “to make Denver proud of the development.”

When the Denver Hilton and Zeckendorf Plaza opened four years later, the complex was embraced as Denver’s answer to Rockefeller Center. The slab-shaped Hilton at 16th Street and Court Place served as a 22-story bookend to an airy plaza that included a skating rink and the May D&F department store. But the star of the development was the entrance to the department store: a geometric glass paraboloid whose sharply angled roof nearly touched the ground before soaring to a peak three stories high. It was Denver’s first architectural reference to the mountains, a concept we’d see later at Denver International Airport and the new addition to the Denver Art Museum, as well as in Pei’s later achievement: the glass pyramid atop the Louvre in Paris.

If the paraboloid was a gift to Denver, then developer Fred Kummer was the scrooge who took it away. After a 1993 purchase of the buildings, Kummer expanded his Adam’s Mark hotel on the site of the paraboloid and plaza. He steamrolled the city into approving his new design: a clunky black box adorned with shiny brass, exposed Hollywood lights, and chandeliers—the kind of faux opulence that had gone out of style decades earlier.

Last February Kummer sold the hotel for $176 million. Now operated by Sheraton, it’s getting a $70 million renovation to upgrade the lobby and rooms and hotel restaurants. The new owner is also considering conversion of several street-level conference rooms into retail shops. Although the original spirit of the plaza and its paraboloid are lost for good, new plans for the site may restore some of the liveliness that made this one of Denver’s proudest places.