The D.C. office of law firm Curtis, Mallet-Prevost, Colt & Mosle LLP has relocated its headquarters to larger space downtown.

The firm said that its new location, on the top floor of 1717 Pennsylvania Ave. NW, more than doubles the size of its offices and will allow for continued expansion of its practice.

"This relocation marks an important step in Curtis’ ongoing expansion in Washington,” said D.C. Managing Partner Daniel Lenihan.

The firm said that it has added four senior lawyers to its D.C. office since December 2008.

According to its Web site, Curtis has three U.S. offices with 16 professionals working in Washington, five working in Houston and more than 100 based in New York. In addition, Curtis has 10 international offices.

K&L Gates LLP, Pittsburgh’s largest law firm, said Monday it has established an office in Warsaw, marking its 36th location and third new site so far this year. It is the first Pittsburgh-based firm to open an office in the Polish city.

The office is expected to open March 15. K&L Gates hired a team of lawyers from Hogan & Hartson Jamka, the Warsaw office of Washington, D.C.-based Hogan & Hartson LLP, to staff it. Maciej Jamka will serve as administrative partner of K&L Gates’ Warsaw office which K&L Gates Chairman and Global Managing Partner Peter Kalis said via e-mail will include “approximately 30 lawyers.”

Kalis said Warsaw is a strategic location. “Poland is a Top 20 global economy and one that has withstood the challenges of the global financial crisis,” Kalis said in a prepared statement.

In January, K&L Gates opened offices in Tokyo and Moscow. It employs roughly 2,000 lawyers, including 237 in Pittsburgh, and topped $1 billion in 2009 revenue.

K&L Gates expects to move into new offices in Downtown Pittsburgh in One Oliver Plaza, a few blocks from its present home in the Henry W. Oliver Building, later this month. The date has not been disclosed publicly.