London Duck Tours (previously Frog Tours) start in a conventional fashion from the rear of County Hall, crossing the river via Westminster Bridge to travel round Parliament Square, Trafalgar Square, Piccadilly, Buckingham Palace and Westminster Abbey. Then they cross Vauxhall Bridge and take a slipway down the side of the MI6 Building – into the Thames. The final half hour of the 80-minute tour is a boat trip along the river to the London Eye and back. The tour 'buses' are four adapted DUKWs developed by General Motors during WWII. The D-Day Duck Tour features character tour guides revealing important WWII sites, in authentic vehicles built for D-Day.