The Boston Redevelopment Authority has approved two new towers that will border the landmark Christian Science Plaza in the Back Bay, including a 691-foot hotel and condo tower along Belvidere and Dalton streets.

At a BRA meeting Thursday evening, developers presented revised plans for the lots, which will include the 300 hotel rooms and 170 condo units in the large tower. A second, mid-rise building will have an additional 255 condo units. Developers also plan to expand the existing parking garage beneath the plaza, but the expanded space will add only 113 additional parking spaces to the current garage.