Predella Panel, The Pisa Altarpiece

The scene on the left demonstrates Masaccio's skilful use of linear perspective, right down to the foreshortening of the halo of St Peter. The action appears to take place in a space behind the picture plane, and the figures within this space appear as solid three-dimensional objects. The two men on either side of St Peter appear to lean forward in space, out towards the viewer, as they hammer in the nails on the cross.

This is a panel from the lower edge of an altarpiece, known as the 'predella', commissioned for the church of Santa Maria del Carmine in Pisa. The altarpiece was unfortunately taken apart, and to date only eleven panels can be conclusively attributed to it. The central panel depicts the Virgin and Child. This section shows two dramatic and violent spectacles of martyrdom from the New Testament. Each scene is separated by a band of gold leaf. On the left, St Peter is nailed to a crucifix. He asked to be crucified upside down so that he would not be undeservingly compared with Christ. On the right, St John the Baptist is about to be beheaded by King Herod's men at the request of Salome. 

This Tempera on panel is housed in the  Staatliche Museen, Berlin, Germany