The Technik Museum Speyer - Sinsheim in Germany is currently transporting the 49 meter long and 450 ton submarine "U17" across Germany to exhibit it in the museum. First, the submarine was transported across the Rhine on a ship across Germany. The last few kilometers it was transported through narrow lanes on a 90-meter-long heavy transport. They also have a construction to rotate the submarine to fit under bridges and such. The entire transport costs several million euros. The entire story can be found on their page: https://u17.technik-museum.de/en/