The IBM building downtown at the corner of Lafayette and North streets was the site of a topping off ceremony Monday signaling the completion of ironwork on the nine-story structure.

The IBM building is on schedule to open in April or May. More than 200 employees are expected to be working at the building when it opens. By 2016, IBM expects it will have 800 employees at the site.

The building is the centerpiece of a public-private development that will include 525 Main, a 10-story development with 85 luxury apartments. 525 Main is set to open by the end of 2015.