Liverpool was first connected by road to its Wirral neighbour on Wednesday, July 18 1934, when the Queensway - or Birkenhead - tunnel opened to the public.
Nearly 40 years later, the tunnel became one of a pair with the opening of the Kingsway - or Wallasey - tunnel on Thursday, June 24 1971. Today both tunnels are a vital vein in and out of the city with 25 million vehicles and counting travelling through them each year.
Though both tunnels were excavated similarly through sandstone, the Birkenhead tunnel, built dozens of years before the Wallasey tunnel, is considered a triumph of early 1900's civil engineering due to the lack of technologies which are taken for granted today. However, both tunnels were not built without their own challenges.
