The Strong Building was an office building in Chicago that the Tribulation Force had used as a safe house during the midpoint of the Tribulation from "The Mark" to "The Remnant", during when Chicago was devastated, deserted, and considered off-limits due to false reports of radioactivity from a nuclear missile strike. It had executive office suites, a parking garage, and a treasure trove of computers and other valuable items such as high-powered telescopes. David Hassid had allowed the Tribulation Force access to this building as they were moving out of their previous safehouse in "The Indwelling". Members of The Place had also moved into the building to stay with the Tribulation Force until they deserted Chicago prior to an actual nuclear missile that destroyed the city.