The left door (facing the reliefs from outside the cathedral) is 328 cm high and 84 cm wide, the right 323 cm high and 83 cm wide. Both are between 1.5 and 2.5 cm thick. They were cast in bronze using the lost wax casting technique in a mixture of copper, tin with a small amount of lead, with some fine detail being added after casting by engraving tools. The left leaf was cast in one piece, but the right was made in 24 cast sections which were then soldered together. Both the lion-headed knockers, which do not align correctly, were also cast separately and soldered. The doors of Hildesheim Cathedral, of about 1015, had pioneered the casting of a large door mostly covered with reliefs in a single piece, which was considerably more difficult than the usual technique of earlier Italian bronze doors, which used bronze relief casts fixed to a wooden core. Plain doors with no figurative decoration had already been cast whole in Germany - for example for Charlemagne's early 9th century Palatine Chapel at Aachen, following Roman techniques preserved by the Byzantines. The Gniezo left door follows the Hildesheim method. The relief is also typically much higher on the left door, as much as 75% on some figures, where few on the right door reach 25%. Around the central panels runs a decorative frieze of Mosan-style "rinceaux", or scrolling foliage, with small figures of astrological personifications and other subjects at intervals.