Turn your back on a favorite old city for a few years and what happens? All of a sudden rough-and-ready Denver has taken on a patina of sophistication and culture. Oh, the jeep still seems to be the preferred mode of transportation and down vests far outnumber furs, but otherwise the Mile High City is a cow town no more.
Denver's downtown boom I had heard about, so I wasn't bowled over by the parade of glass towers on 17th Street - the Wall Street of the Rockies. I was surprised, though, to hear a friend say that ''the bottom has dropped out on the gas and oil industry here, and there's a lot of empty office space in those buildings.''
Down at street level, things seemed much healthier. Denverites were lolling about the newly completed 16th Street Mall in the afternoon sun. Just to the west, the white-topped Rockies reminded you it was still very much winter, but here in the 50-plus warmth people were pared down to shirtsleeves and sitting in white metal chairs and wood benches at the center of the flagstone mall. I picked up a sandwich at Goldie's Delicatessen and took an outdoor seat myself.
The mall, which Denver hopes will revitalize a sagging downtown, stitches together the three big department stores - May-D&F, the Denver, and Neusteter's - and various other shops and businesses on its march from the gold-domed State Capitol Building to Larimer Square. The only vehicles permitted are slow-moving shuttle buses which provide free and frequent service well into the night. Denver, I was glad to see, is making good use of its noble, old downtown architecture, such as the Kittredge Building, an arched, Victorian limestone structure that is home to a mallside restaurant, Marlowe's.
I hopped a bus and headed for Larimer Square, passing the huge and rising Tabor Center, which, though still a few months from opening, already showed a resemblance to New York's Southstreet Seaport and Boston's Faneuil Hall Quincy Market. The shuttle-bus terminal is a short walk from Larimer Square, which I remembered as a block of renovated turn-of-the-century brick buildings taken over by boutique and restaurant establishments. Business has since spread to the neighboring streets, and the Victorian facades have taken on a spanking clean and sandblasted appearance. But the old Denver still shone through in the garishly green Rocky Mountain Seed Company, the Crest Office Supplies shop with its battered vintage typewriters, and the man in a wheelchair playing a saxophone on the sidewalk.
No doubt the biggest change in town is the arrival of the Denver Center for the Performing Arts, a clutch of old and new downtown buildings tied together by a glassy galleria roof. Though the Denver Center is compared to Lincoln Center and Kennedy Center, there is a key distinction. ''They are landlords,'' said a Denver Center official, ''but we are more. We do at least 30 of our own productions a year.''
We were exploring the Helen Bonfils Theater Complex, a delightful combination of rose carpeting, concrete, and glass that houses four theaters. We peeked into The Space, where an afternoon production of Shakespeare's ''Romeo and Juliet'' was being performed in contemporary dress. How odd to see the men of Verona in black business suits. Denverites can choose from four plays in repertory at any time, and the ticket prices are just $7 to $15, or about half as much in preview.
Another Bonfils Theater tenant is the Denver Center Cinema. Do not expect to cuddle up to a carton of popcorn or hear a
wheezing projector in this state-of-the-art movie house, which shows old and classic films from Chaplin to Truffaut at $3 a seat. The shame is that more people haven't enjoyed the plush and spotless theater so far. ''One reason for the small crowds,'' said the center official, ''is that because it's a noncommercial theater we can't advertise.'' But one can always phone for the daily schedule, at 892-0983. Meanwhile, the anchor of the new center is the Boettcher Concert Hall, a sort of orchestra in the round with white-blond high-backed wood seats and rust upholstery.
Up the hill near the Capitol, the Denver Art Museum is doing more and more with Western and native American art, and indeed that afternoon a colorful cowboy exhibit was being mounted. If there was once a void in such art, it has been filled with the arrival of the Museum of Western Art, located in the heart of downtown. This decorative red-brick 1880 building, reopened last December, is the inspiration of a Denver cattleman and feedlot entrepreneur, William Foxley, who has amassed perhaps the last great Western art collection. Russell, Remington, Bierstadt, Moran, O'Keeffe, and many others are well represented.
Another chunk of old Denver still very much extant is the Brown Palace, a hotel of legendary proportions across the street from the Museum of Western Art. The triangular, brownstone building was opened in 1892, and one wonders if its eight-story atrium with stained-glass skylight and iron-filigree balconies inspired the inside-out Hyatt hotel design of recent years. President Eisenhower made his summer headquarters on the 7th floor of the Brown Palace, and that suite of rooms is still intact and rentable, complete with the divot Ike dug out of a wall practicing his golf swing.
I haven't even mentioned Denver's sprawling and excellent park system - little Cheesman is my favorite park - or old Union Station, or the rebuilt Oxford Hotel, or the surprisingly good representation of restaurants. But first things first in the cow town that is no more.