Denver, Colorado - The big surprise about sprawling Denver is the 2-kilometre-long pedestrian zone that runs in the heart of the city.

The 16th Street Mall joins the staid, gold-domed Colorado state Capitol building with the rough and tumble refurbished warehouses of Lower Downtwon, or LoDo.

In between are pricey shops and Starbucks, department stores and souvenir stands, restaurants and bars, and a gaggle of classy hotels, some of them reminiscent of the Old West - like the Brown Palace Hotel.

People with tired feet or disability can board a free bus that runs unobtrusively along the tree-shaded strip. Several doors open along its length when it stops, like a subway train, making boarding and disembarking easy.

"It's been 40 year since I rode a bus!" joked a middle-aged man who climbed aboard with three others.

The suburban dwellers had come downtown to gawk at the thousands of protestors promised in media coverage in the lead-up to this week's Democratic presidential convention and nomination of Senator Barack Obama, the first African-American candidate from a major party in US history.

When the group got to Civic Center park next to the Capitol, where police had issued permits for demonstrators, there was almost no-one there.

Police were also baffled. Thousands of reinforcements had been ordered from around the state, along with secret service and FBI security units.

At the park, a dozen or so police officers from outlying Aurora sat idly on a wall. Could they please help a reporter to find the protesters?

"You tell us," they chorused, then laughed with the laid-back attitude typical of the western city.

A quick circuit of the park found several fringe groups, like the Revolutionary Communist Party which charges the political system is racist and Obama a sheep in wolf's clothing.

Another stand was selling a satirical book "Goodnight Bush," a takeoff on Margaret Wise Brown's children's classic, "Goodnight Moon."

In fact, the real political action had moved back down along the 16th Street Mall, where hundreds of convention delegates, journalists and Democratic officials - the apparent target of the protestors' messages - were riding the free bus, their credentials swinging from their necks.

Occasionally, a demonstrator flashed a poster-mounted message through the bus door when it opened.

Groups of people dressed in orange jump suits like the ones worn by prisoners at Guantanamo Bay roamed the pedestrian zone. One day, they demonstrated the torture technique known as water-boarding at the nearby federal building.

Despite their low numbers, more than 100 demonstrators have managed to get themselves arrested for blocking streets or refusing to cooperate with police. In one case, Denver's finest used pepper spray.

At the bottom of 16th Street, in the heart of LoDo, a street vendor sold stuffed-doll images of Obama and the defeated Hillary Clinton. Campaign button sellers abounded.

One street over, on 15th Street, the Ernest Fuller Fine Art gallery occupies what Fuller, 53, said was the oldest commercial structure in Denver - the Wells Fargo building, built in 1874.

Fuller's pricey western art - a bronze statue of a Pawnee Indian warrior fetches 33,000 dollars - typifies the transition of a neighbourhood that 20 years ago was abandoned and decaying.

"In 1980, you probably wouldn't have wanted to be down here," he said.

But now he worries about another transition away from the flourishing boutiques and galleries. The recently-built Coors field, home to Denver's new expansion baseball team the Rockies, has brought change and attracted more restaurants and condominiums.

Across the street from Fuller is a building with a faded sign, "Rocky Mountain Seed Company."

Until two years ago, the firm still sold seeds from stacked little wooden drawers. The floors were hardwood, Fuller said.

Now the building is slated for renovation into shops.

Under fluffy cumulonimbus clouds that strafe Denver's blue summer sky each afternoon along the nearby Rocky Mountains, Fuller looks around mournfully from the sidewalk outside his door.

He can see five cranes he can see that are further transforming the neighbourhood.