Archived: 21 Cottage Street #2 Chelsea, MA 02150. A penthouse three bedroom+ office, two full bath condo with garage parking for sale by Jeff Bowen. 21 Cottage Street Unit 2, Chelsea — a 3-bed, 2-bath condo (1,478 sq ft). Sold for $374,000 on June 13, 2016 (MLS #71981493).