Auckland's $1.4 billion Waterview Tunnel has been officially opened by the Prime Minister.
Bill English has unveiled a plaque in a ceremony at the tunnel entrance in Mt Roskill, assisted by the Finance and Infrastructure Minister Steven Joyce and Transport Minister Simon Bridges.
The twin three-lane 2400 metre tunnels join the Southwestern Motorway to the Northwestern Motorway.
The Waterview Tunnel is now the longest in the country, taking the record from Christchurch's Lyttelton tunnel which is 1,970 metres long.
The public will be able to walk and bike through the tunnels during special open days in the next two weeks.
The tunnels will open to traffic in early July.