Blisworth Tunnel sections lined with pre-cast concrete rings. It was also used to test out the materials that were later used on the Channel Tunnel. An unused ring is on display near the south portal. Blisworth Tunnel Blisworth Tunnel is a canal tunnel on the Grand Union Canal in Northamptonshire, England, between the villages of Stoke Bruerne at the southern end and Blisworth at the northern end. The northern end is about from the northern end of the Grand Junction Canal at Braunston, Northamptonshire and the southern end about . At 3,076 yards (2,813m) long it is the third-longest navigable canal tunnel
Riqueval Tunnel Riqueval Tunnel The Riqueval Tunnel is a -long tunnel on the St Quentin Canal, close to the commune of Bellicourt, in the department of Aisne, France. It connects Bellicourt with Bony. It was constructed as part of the St Quentin Canal between 1801 and 1810, on the orders of Napoleon. The tunnel remains in use, and can be traversed using a chain boat. Along with the Mauvages tunnel, on the Marne–Rhine Canal, it is one of the last locations in the world where a system of chain towing is still in operation. It was the longest tunnel in the world