Last one from Denver: the railyards near Union Station.
This city exists because of the railroad and, unlike many US cities which can say the same thing, Denver still shows it.
Union Station itself is a miniature masterpiece, beautifully restored and with - of course!
- a wonderful beer bar serving 30+ excellent local beers.
Located in a reasonably walkable neighbourhood, it connects Amtrak, buses, and a decent light rail system (good: runs on time, pretty frequent, no turnstiles to board; very bad: mostly bizarre station placement, miles from anything) that connects with the airport.
Complete with snow, this picture neatly summarises my impression of a nice little city.