Construction of Vista Tower reached an important milestone last week. Concrete was poured on the 50th floor of Magellan Development's Jeanne Gang-designed, Lakeshore East skyscraper, bringing the building to the halfway mark of its 101 stories.

Vista Tower reached this point in less than 20 months, a rapid pace of construction aided in part by two mild winters, and it has progressed amid speculation that Magellan's partner in the project, Dalian Wanda Group, is entertaining selling its stake in the building.

Construction crews also completed the first part of Vista Tower's stacked frustum design, which will allow crews to focus on the taller portions of the building.

Vista Tower is slated to complete in 2020 and to top out at 1,198 feet, which would supplant Aon Center as Chicago's third-tallest building. Magellan Development Senior President of Sales Leila Zammatta said 40% of Vista's 406 luxury condominiums are sold.

Magellan set up a series of webcams so those interested can keep up with construction in real time.