LERA was structural engineer for the original convention center in the 70's. The expansion was completed in 1996 and the entire renovated and expanded center began hosting conventions in April 1997. The $160-million expansion consisted of a 750,000-sf (89,680-sm)addition that tripled the size of the original building. The new facility includes a below grade, 300,000-sf (27,870-sm) exhibit hall, the addition of 45,000 sf (4,180 sm) of meeting rooms, and a new 36,000-sf (3,345-sm) ballroom, plus accompanying mechanical and public spaces. An innovative three-chord truss system created 180-ft x 600-ft (55-m. x 180-m) column free exhibit space in the exhibition hall. Completed on a fast-track schedule, the existing Baltimore Convention Center was kept fully operational during construction of the new expansion.