Question: The Old Tung Chung Pier at the mouth of the Pearl River is located on the largest island in what city?
Context: Lantau Island (also Lantao Island; ) is the largest island in Hong Kong, located at the mouth of the Pearl River.  Administratively, most of Lantau Island is part of the Islands District of Hong Kong.  A small northeastern portion of the island is located in the Tsuen Wan District. Tung Chung, meaning 'eastern stream', is an area situated on the north-western coast of Lantau Island in Hong Kong.  Being currently one of the latest generations of new towns, it was formerly a rural and fishing village round Tung Chung Bay, and along the delta and lower courses of Tung Chung River and Ma Wan Chung in the north-western coast of Lantau Island.  The area was once an important defence stronghold against pirates and foreign military during the Ming and the Qing dynasties. The Tung Chung Line is one of the eleven lines of the MTR system in Hong Kong, linking Tung Chung with Hong Kong Island.  A part of the Tung Chung Line was built along with the Kap Shui Mun Bridge and the Tsing Ma Bridge.  The line currently travels through eight stations in 27 minutes along its route.  The line is indicated by the colour orange. Tung Chung East () is a proposed MTR station of Tung Chung Line at the east of Tung Chung, Lantau Island, New Territories, Hong Kong.  This station will be on ground level, similar to Sunny Bay Station, so as to not affect the existing railway network. Pak Kung Au (伯公坳), also known as Tung Chung Gap, Tung Chung Au (東涌坳), is a mountain pass along Tung Chung Road on Lantau Island, Hong Kong. Tung Chung New Development Ferry Pier () or Tung Chung New Ferry Pier () is a ferry pier in Tung Chung Waterfront Road (), Tung Chung, Lantau Island, New Territories, Hong Kong.  It was built to replace Tung Chung Old Ferry Pier in Ma Wan Chung (). Tung Chung Fort (; 東涌所城 during the Qing dynasty) is a fort located near Tung Chung, on Lantau Island, in Hong Kong.  Close to Tung Chung Road, the fort is surrounded by the villages of Sheung Ling Pei () and Ha Ling Pei ().  It has a companion Tung Chung Battery on the coast. The Ngong Ping 360 is a gondola lift on Lantau Island in Hong Kong.  Intended to improve tourism to the area, the aerial lift was previously known as Tung Chung Cable Car Project before acquiring the Ngong Ping 360 brand in April 2005.  It consists of the Ngong Ping Cable Car, formerly known as the Ngong Ping 360 Skyrail, and the Ngong Ping Village, a retail and entertainment centre adjacent to the cable car's upper station.  Ngong Ping 360 connects Tung Chung, on the north coast of Lantau and itself linked to central Hong Kong by the Tung Chung Line, with the Ngong Ping area in the hills above.  This is home to the Po Lin Monastery and the Tian Tan Buddha, both already significant tourist attractions in their own right.  Before Ngong Ping 360's opening, the only access was via a mountain road and bus service. Tung Chung Bay () is a bay in at the west of Tung Chung, Lantau Island, Hong Kong, near North Lantau New Town and Hong Kong International Airport.  It is also the location of Old Tung Chung Pier. Tung Chung West () is a proposed MTR terminus station of Tung Chung Line at the west of Tung Chung, Lantau Island, New Territories, Hong Kong, which would follow on from Tung Chung Station.  When Yat Tung Estate (Trad.  Chinese: 逸東邨) in Tung Chung West was constructed, the MTR Corporation and the Hong Kong SAR Government reserved a site to build the station.  Due to insufficient population there, the station has so far not been constructed.
Answer: Hong Kong