The best way into Denver is by taking the train to Union Station, a cavernous Beaux Arts building with a barrel-vaulted ceiling, giant chandeliers wrought in brass and milk-white glass, and arched windows as tall as trees. From there, it’s only a couple of blocks to a popular hiking trail. People like to walk along Cherry Creek, following the path as it connects to a highly developed network populated by skaters, mountain bikers, joggers, and dogs. The trail wends through the city center to join another, and then another, along South Platte River, where runners meet kayakers and fly-fishers.…