In the context of Holy Trinity (Masaccio), analyze the Altar of the Description.
Originally, the design included an actual ledge, used as an altar, physically projecting outward from the now-blank band between the upper and lower sections of the fresco; further enhancing the sense of depth and reality in the work.  Constructed as a pillared-shelf ~5 ft. above the floor, and estimated to be about 60 cm. wide, the altar-table's appearance would have been intended to match and/or complement the painted architecture.  Its facing-edge and upper surface integrating with the fresco's steps and archway; and its supporting pillars, both real and illusory, combining with the shadows caused by the over-hang to create a crypt-like effect for the tomb beneath.  The upper section of the fresco still retains traces of candle-smoke and heat-effects from use of this altar.
fresco