into fertilizer. The US Coast Guard has a base in Boston, and the sail frigate USS Constitution ("Old Ironsides") is berthed at the former Charlestown Navy Yard, now part of the Boston National Historical Park. The park is also home to the USS Cassin Young, a World War II-era Fletcher-class destroyer and now a museum ship. The park's Drydock Number 1 was completed in 1833 and first used by the Constitution. It is now used to overhaul historic ships, including Constitution in 1992 and Cassin Young in 2007. Two other pre-World War II-era dry docks in the harbor are still operational (as of 2014), including Dry Dock Number 3 — one of the largest dry docks on the U.S. East Coast — which regularly repairs ships for the Military Sealift Command. These are located at the former South Boston Naval Annex. MBTA Boat, water taxis, and private ferries and small cruise boats also use docks at Rowes Wharf, Long Wharf, Boston Navy Yard, Logan International Airport, Hewitt's Cove in Hingham, Pemberton Point in Hull, and the Fore River Shipyard in Quincy, and a number of small docks at destinations around the harbor. The Boston Harborwalk provides public access to much of the harbor's edge. Piers and wharves Boston's port was historically served by many more wharves and pier facilities. Although Massport maintain the more notable ones, a handful of docking facilities in the Boston Harbor are maintained by private interests or other state agencies such as DCR. Further, some wharves have been converted to residential condominiums, or hotel accommodations. The Port's current and former wharves include: Piers Boston Fish Pier Commonwealth Pier Fan Pier Piers Park Piers Park Sailing Center Windmill Pier Wharves Battery Wharf Burroughs Wharf Central Wharf Children's Wharf Commercial Wharf Constellation Wharf Constitution Wharf Flagship Wharf Griffin's Wharf India Wharf Lewis Wharf Lincoln Wharf Long Wharf Lovejoy Wharf Rowes Wharf Russia Wharf Sargent's Wharf T Wharf Union Wharf Foreign Trade Zone Massport manages Foreign Trade Zone (FTZ) No. 27, which includes many privately owned and port-owned sites located throughout Suffolk County, Massachusetts. The following Sub Zones are a part of The Port of Boston FTZ No. 27: 27C Lawrence Textile 27D GM 27E Polaroid 27F Polaroid 27H Polaroid 27I Polaroid 27J Polaroid 27K Polaroid 27L AstraZeneca LP 27M Reebok International 27N Spectro Coating Corporation d/b/a Claremont Flock, LLC Traffic and statistics In 2015, the port handled 237,000