State Street was blocked from Wacker Drive to Illinois Street, and CTA buses are being rerouted during a death investigation at the Marina City apartments.
Police say someone jumped from the 28th floor of the iconic towers.
Authorities received the report at 8:45 a.m. The 53-year-old man was dead at the scene.
By about 11 a.m., the streets had been reopened to traffic and CTA buses were back on their normal routes, spokeswoman Wanda Taylor said.
The combination residential/commercial Marina City complex occupied an entire city block on State Street on the Chicago River. It consists of two 65-story towers.