Block 185, Office skyscraper in Downtown Austin, United States

Block 185 is an office tower in downtown Austin with a distinctive curved glass facade shaped like a sail. Its 35 floors contain office space, parking facilities, and ground-level retail, with direct connection to the Second Street shopping area.

The land was originally planned for use as a penitentiary starting in 1839, then later became a water treatment facility. The site was sold in 2012 and developed into the current structure.

Google signed a lease for the entire building on January 31, 2019, the same day the Austin American-Statesman published the first renderings. The lease runs to 2038, but Google delayed moving staff in after the 2022 completion, and the tower stood empty until late 2025. The name Sail Tower comes from the curved glass facade that bends away from Shoal Creek.

The tower occupies the block bounded by Shoal Creek to the west, Nueces Street to the east, Second Street to the north and Cesar Chavez Street to the south, in the Second Street District. Its address is 601 W. 2nd St. The setback from Shoal Creek and Lady Bird Lake shapes the south side as receding terraces and curves the west glass facade away from the creek.

The tower's sail-like curve is a direct result of setback rules tied to its proximity to Shoal Creek and Lady Bird Lake; on the south side facing the lake, the setback appears as a series of receding terraces. The building topped out in July 2021 at 594 feet, making it the tallest office tower in Texas outside Houston or Dallas.