Hebrew SeniorLife has executed a new 13,835 s/f lease for its executive offices at 300 First Ave. The Colliers Meredith & Grew team of executive vice president James Elcock and vice president Elias Demakes represented both Hebrew SeniorLife and the landlord, Three Hundred Realty Trust. 300 First Avenue is a three-story, 75,000 s/f class A office building located near Rte. 128. Amenities include on-site ownership/management, structured parking and shopping and restaurants located within walking distance.