One American Center, Skyscraper in downtown Austin, United States.

600 Congress, formerly One American Center, is a 32-floor, 400-foot office tower at West 6th Street and Congress Avenue in downtown Austin. Houston-based Morris-Aubry Architects designed the postmodern building with three stair-stepped tiers clad in pre-cast limestone trimmed with brown granite; the ground-level facade has notches that suggest individual storefronts.

Construction began on August 16, 1982, and the building was completed in 1984, developed by Rust Properties. It replaced a two-story Art Deco Woolworth's store that had housed a five-and-dime. It stood as Austin's tallest building until the Frost Bank Tower was finished in 2003, and in 2017 it was rebranded 600 Congress.

The building's ground-level facade has notches cut into it to mimic a row of individual storefronts, a nod to the Woolworth's department store it replaced. Its granite comes from two places: Sunset Red from Granite Mountain near Marble Falls, Texas, and Charlie Brown granite from Oklahoma, cut and polished in Puebla, Mexico.

The tower stands at the northwest corner of West 6th Street and Congress Avenue, in the Financial District of Downtown Austin. Its ground-level facade has notches cut to look like separate storefronts, so the base reads as a row of shops rather than a single lobby wall. The expanded granite sidewalk along Congress Avenue is lined with two rows of Texas red oak trees.

Until October 2022, the first 300 people to raise $1,500 for Make-A-Wish Central and South Texas could rappel 32 stories down the facade in the "Over The Edge" fundraiser. The building was Austin's tallest from 1984 until the Frost Bank Tower opened in 2003.