At 961 feet, this skyscraper falls just short of supertall status but its design and distinctive crown make a curious complement to neighboring Willis Tower.

311 South Wacker stands as a symbol of the evolution of skyscraper design from the glory days of the 1970s to the late '80s and early '90s. Here are four things you may not know about the 65-story building.

1. It Has Held A Couple Of Notable Records

Chicago developers love building reinforced concrete skyscrapers. When it was delivered in 1990, 11 South Wacker was briefly the tallest reinforced concrete building in the world until Two Prudential Plaza was completed that same year. Chicago is still home to the tallest reinforced concrete building in the world: Trump International Hotel & Tower.

311 South Wacker held another distinction for a quarter of a century. It was the tallest building in the world known only by its street address until New York's 432 Park Ave opened last year.

2. The Lobby Was Designed To Eventually Be A Pedway

311 South Wacker's two-level lobby is a breathtaking sight. Its glass ceiling reminds us of the Rookery Building's light court and serves as a 
"winter garden" that provides respite from the harsh Chicago winters.

But it was supposed to be more than that. The atrium's lower level was supposed to double as an underground pedestrian connection to nearby Union Station, which is preparing for modernizations as part of the Union Station Master Plan. A decommissioned streetcar tunnel would have connected the two buildings.

3. That Beautiful Dome

Willis Tower's antennas are imposing, especially when they're lighted for various holidays, but 311 South Wacker's 105-foot-tall translucent crown may be more breathtaking, especially during this holiday season. The four surrounding turrets are illuminated by 1,852 fluorescent tubes, and the center has a single lantern. As a nod to the architecture of Chicago's past, the top was inspired by the neo-Gothic design of Tribune Tower.

4. The Outdoor Garden

These days, setting aside some land for public space is essential for any downtown construction project. But it was rare to see that in the late '80s. This makes 311 South Wacker's one-acre outdoor park a trendsetter. It's an oasis for office workers and tourists during the warmer months, allowing all to remove themselves ever so briefly from the pedestrian bustle a few steps away.