Architecture firms NBBJ and Chan Krieger Sieniewicz have merged to create a team of more than 700 architects, urban designers, planners and interior designers.

The Chan Krieger Sieniewicz team, including its five principals, will continue in their current roles. As part of the transition to the NBBJ name, the Cambridge office will operate as Chan Krieger NBBJ.

The merger gives Seattle-based NBBJ, which already operates a project office in Boston, a larger presence in New England, according to a statement.

More than three years of collaboration as the design team behind the new 530,000-square-foot Building for the Third Century at Massachusetts General Hospital (MGH) led to a growing interest by principals in both firms to establish a more formal and far-reaching alliance, according to a statement.

"We were initially brought together with NBBJ when MGH suggested we team up and combine what the client saw as complementary abilities," said Alex Krieger, founding principal of Chan Krieger Sieniewicz and professor at the Harvard Graduate School of Design. "As we worked with our colleagues at NBBJ, we realized we shared the same values and studio culture, only on a different scale."

"Since that introduction three years ago, we learned a lot about each other and came to realize the value we could provide to clients by combining the strengths of both organizations," said Scott Wyatt, managing partner of NBBJ. "NBBJ is known for our deep market experience in healthcare, education, corporate and commercial design. Chan Krieger Sieniewicz is known in Boston and internationally for its world-class depth in architecture and urban design. Integrating this experience advances what we can together offer clients, particularly on complex urban projects in the U.S. and overseas."