Says this travel site:

The Stevens was the largest hotel in the world when it opened its doors to guests. Six years later, Ernest Stevens was on trial for embezzlement, his brother committed suicide after the family’s insurance business went bankrupt and the U.S. Army purchased the Stevens Hotel in World War II to house soldiers.

Think "Titanic."

It wasn't the largest for long. Lists of Chicago Hotels say it's the third biggest, behind the godless Hyatt Regency and the Palmer House. But the Palmer has 1,639 guest rooms. The Stevens has 3,000. Perhaps the other hotels are "largest" in terms of overall space, such as ballrooms and lobbys, but it seems odd that the place with 1200 more rooms than its nearest competitor isn't the Largest, period. Perhaps it's because the rooms have been consolidated into 1500, but that wasn't the case at the time this matchbook was printed.

More on the hotel & its history here. Highly recommended.