LOUISVILLE — Century Park Plaza, built by O’Connor Construction, filled up quickly recently with three small companies, apparently part of a continuing trend of Boulder companies to move out of the city.

Two law firms and a financial firm moved into the new building, located at 287 Century Circle Drive, Louisville, near McCaslin Boulevard and U.S. 36. Another 2,200 square feet is still available for lease in the 11,000-square-foot building. Lease rates are around $15 per square foot, said Pat Butler, a principal with Lamm, Freeman and Butler, a law firm that co-owns the building.

“People all have a learning curve,´ said Michael Guidarelli, an O’Connor Construction spokesman. “They can have a P.O. box in Boulder, but they don’t have to be in Boulder. More and more smaller companies are considering this.”

Connolly, Halloran and Lofstedt, a law firm, moved to the Century Park Plaza building in September from its office on the Hill in Boulder. Company principals spend a lot of time in court in Denver, so it makes sense to be close to the Denver/Boulder turnpike, said Tom Connolly. “We had no parking where we were before,” Connolly said.

Lamm, Freeman and Butler formerly was located in the Water Street complex at the corner of Folsom Street and Canyon Boulevard.

And after standing “on practically every piece of dirt in Boulder for the last three years,” the land in Louisville seemed very reasonable at about one-eighth the cost, Butler said. Financial planning firm Butler and Co. also is located in the building.