There is a luggage storage service a short one minute walk from Union Station in downtown Denver - LUGDEN. You can make a reservation online - lugden.com, call - (303) 747-5600, or show up as a walk-in. They offer hourly, day, overnight and weekly bag storage. Great place to store your luggage if you're on a layover from Denver International Airport, or going to a concert, or headed to a Rockies game at Coors field and want to enjoy yourself without having to lug your bags around.
These things have been incredibly helpful; my daughter has used them for three years now and they keep working every year. I bought two as she has a tall locker, and these things certainly keep her organized. The paint hasn't flaked off the metal after this long, and nothing has come apart. Overall, this is the best locker shelf I've seen out there. Durable, long-lasting, and well worth the money!
The storage lockers were a “pilot,” the kind of small test that city government frequently uses to test a new or controversial idea. The city offered up the lockers for individuals to use for months-long stretches. At the time, city officials warned that “misuse of the lockers, vandalism, or other unanticipated results,” could force them to cancel the project.