Chicago’s under-construction—and increasingly hard to ignore—Vista Tower reached its half-way point on Thursday as crews poured the concrete slab for the 50th of skyscraper’s planned 101 levels.

The milestone occurred relatively quickly—less than 20 months after the Lakeshore East supertall broke ground—thanks in part to two mild winters. With the first of Vista’s three stepped in-line “tubes” now topped-off, the remaining floorplates should continue to rise quickly.

Slated to reach 1,198 feet, the combination hotel and condominium project is the tallest tower currently under construction in Chicago and is poised to eclipse the Aon Center to become the city’s third tallest when complete. Its ranking, however, could soon slip if a proposed 1,422-foot skyscraper next to Tribune Tower is realized.

Vista Tower comes from Magellan Development Group and features a stacked frustum design by renowned Chicago architect Jeanne Gang of Studio Gang in collaboration with bKL Architecture and Hirsch Bedner Associates. Roughly 40 percent of the project’s 406 luxury residences are sold, according to its developer.

The mixed-use project will also see the addition of blue-green exterior glass ahead of its planned 2020 opening. In the meantime, you can follow the remaining action via Vista’s array of webcams.