After two years of planning and fundraising, construction began Thursday on Harvard Medical School's (HMS) newest building, a $250 million research and medical treatment center on the school's Boston campus.

The ceremony--in which Harvard President Neil L. Rudenstine, HMS Dean Joseph B. Martin and Boston Mayor Thomas M. Menino symbolically "broke ground" for the building--signified the start of HMS's most substantial expansion in nearly a century.

Over 100 invited guests and other University officials attended Thursday's festivities. For an institution that has struggled with space constraints for over a decade, the new building's 430,000 square feet of lab space will ease a major problem for HMS, said Eric P. Buehrens '75, associate dean of planning and facilities for the school.

"If you look back at the past decade or 12 years at the Medical School, we've had to add 30 to 40 percent to our lab inventory every few years in order to keep pace with federally funded research institutions," he said. " It's an important new measure to keep the Medical School at the forefront." The new building--called the North Quad--will sit across from HMS buildings on Avenue Louis Pasteur in Boston.

In addition to added lab space for medical researchers, the new building will feature a 600-seat auditorium, as well as kitchen space and lounges conducive to "water cooler conversations" between scientists.

A ten-story tower will top the new facility, which is scheduled for completion in late 2003. Martin said the quarter-billion dollar expansion will be financed by private donations and federal grants primarily from the National Institutes of Health.

In addition, Harvard-affiliated hospitals doing research in the new facility will help fund its construction through lease payments after the building is opened. Buehrens said HMS had no specific plans for increasing undergraduate research opportunties as a result of the added lab space in the North Quad.

But as a home to both doctors and researchers, the new building will bring together both clinicians who deal with patients and academic scientists.