The Holy Blood altarpiece is in the gallery of the west choir and portrays the Last Supper. The shrine enclosure for the altarpiece takes the form of a chapel with a glazed polygonal miniature chancel. This was a commission by the town council and the contract given to the sculptor was very detailed, specifying exact dimensions, scenes and figures. The altarpiece was to be a giant reliquary for the drop of Christ's blood that was preserved at the church and was a greatly revered object of pilgrimage. The iconography of the altarpiece was dictated by this relic: the main scene shows the Last Supper, when Christ instituted the Eucharist by lifting up bread and wine and saying to the Apostles 'This is my body and blood'. The scene as interpreted by Riemenschneider is an animated gathering focused around the personal drama taking place.