Cubist Pharmaceuticals Inc. has opened its newly expanded research and development facility at its Lexington headquarters.

The facility, at 65 Hayden Ave., which totals 104,000 square feet, includes laboratory space for research and development around antibiotics and other products, a molecular modeling room, office space and conference rooms. Built to the LEED Silver Standard, the building features high efficiency plumbing and lighting fixtures, distribution controlled heating and cooling systems, and updated mechanical equipment and Energy Star-rated appliances.

Cubist held an official opening ceremony, which included company President and CEO Michael Bonney and U.S. Sen. Scott Brown, Friday.