Birkenhead is a town within the Metropolitan Borough of Wirral in Merseyside, England. Historically in Cheshire, it is on the Wirral Peninsula, along the west bank of the River Mersey, opposite the city of Liverpool. The Birkenhead Urban Area The Birkenhead and Tranmere electoral ward, covering a much smaller area, had a population of 15,879. The recorded history of Birkenhead began with the establishment of Birkenhead Priory and the Mersey Ferry in the 12th century. During the 19th century Birkenhead expanded greatly, becoming a town as a consequence of the Industrial Revolution, with Birkenhead Park and Hamilton Square being examples of the era. Around the same time, Birkenhead gained the first street tramway in Britain. Later, the Mersey Railway connected Birkenhead and Liverpool, with the worlds first tunnel beneath a tidal estuary. Birkenhead is perhaps best known for the shipbuilding of Cammell Laird, and for the towns seaport. In the second half of the 20th century, the town suffered a significant period of decline, with containerisation causing a reduction in port activity. During the first half of the 21st century, the Wirral Waters development is planned to regenerate much of the dockland.