Not six months after Covington & Burling signed a letter of intent to move its headquarters into the City
Center DC
development currently under construction, two other D.C. law firms are close to finalizing moves into planned buildings downtown.

Arnold & Porter, which considered CityCenter before Covington signed on in May, has signed a letter of intent with Boston Properties to move from 555 12th St. NW into a building the developer plans for 601 Massachusetts Avenue, according to sources familiar with the deal who asked to speak anonymously because they are not authorized by the firm to discuss it.

Boston Properties plans a 470,000-square-foot building for the site, which is to replace the current National Public Radio headquarters after NPR relocates to a new home in NoMa (also under construction). The new Massachusetts Avenue building could be completed by 2015.

A spokeswoman for Arnold & Porter did not return calls. Raymond Ritchey, executive vice president of Boston Properties, declined to comment.

Pillsbury Winthrop Shaw Pittman also has signed a letter of intent for a planned building, at 1200 17th St. NW, a project that will replace the longtime headquarters of the National Restaurant Association. That lease, for about 105,000 square feet, is to anchor a project by D.C. developer Akridge and Mitsui Fudosan America, which bought a majority stake in the project last month.

Christine Nicolaides Kearns, managing partner of Pillsbury’s Washington office, said the firm had a lease that would expire at its current location, 2300 N St. NW, in December 2014 and had been considering other options for more than a year. She said the 17th Street project offered a new building easily accessible by both car and public transit, as well as opportunities for Pillsbury signage on the inside and outside.

Kearns expects to occupy less space despite adding people because of the increased efficiency of new law offices, which do not set aside enormous areas for filing systems, law libraries or administrative staff, functions that Kearns said were “ideal in 1986 but no longer needed now” because of “increased efficiencies,” she said.