BOULDER - Finding 10,000 square feet of office space in downtown Boulder is a challenge for everyone - even if you own about 300,000 square feet of it.

W.W. Reynolds Cos., one of the largest developers and owners of commercial real estate in Boulder, has relocated its headquarters to 1375 Walnut St., which is in the Colorado Building complex.

W.W. Reynolds owns the Colorado Building, which is best known for being the tallest building in downtown. It also built and owns the One Boulder Plaza complex, which is one of the newest commercial developments in Boulder.

W.W. Reynolds is leaving it old 7,500-square-foot space in One Boulder Plaza to accommodate the growth of Holland & Hart LLP, the Denver-based law firm that is expanding its Boulder office, W.W. Reynolds' partner Jeff Wingert said.

"They've been in a growth mode and needed to expand. They were on the entire floor above us, and it made sense. It's something developer/owners do to accommodate good tenants," Wingert said.

W.W. Reynolds' decision to take a space in the basement of the Colorado Building also was a pragmatic one.

"It was the only space in downtown Boulder that was big enough to house our operation," Wingert said.

The company wanted to stay in a property it owns, but in the end it didn't have much choice.

"There weren't really any other spaces that would fit us anyway, even that were outside of our portfolio," he said.

The lobby, basement and first and second floor offices at 1375 Walnut St. are going through an extensive makeover.

"We basically gutted the entire thing," Wingert said.

W.W. Reynolds is taking over the basement, while Newton Running Co. Inc. has relocated its headquarters to the building's first floor.

W.W. Reynolds is determining whether to upgrade the tower, which is at 1919 14th St., Wingert said.