Another attraction from its ancient industrial past is the "Old Crane" of Andernach (Ger. der "Alte Krahnen"), a 16th-century stony land based treadwheel tower crane in diameter and high situated outside the town downstream close to the river bank of the old harbour where it replaced an even older 14th century wooden floating treadwheel crane. For 350 years it was in operation from 1561 to 1911. Two to four men were required to rotate the crane top by means of a huge double ended lever (horizontal wooden bar) attached to the vertical wooden crane "beam" and four others on a (treadwheel men or menials) to operate the huge wooden twin treadwheels (more than in diameter) which lifted and lowered the load—mainly millstones, tuff-stone blocks for the Netherlands and wine casks. This treadwheel crane with stone walls (most cranes had a timber housing) is one of only a few of its kind in Europe to have survived. A prince-electoral order or permission was needed to build and operate such a crane in the times of the Holy Roman Empire.