Excerpt from Wikipedia:
The ornate side entrance to the monastery was designed by Juan de Castilho and is considered one of the most significant of his time, but is not, in fact, the main entrance to the building. This shrine-like portal is large, 32 metres (105 ft) high and 12 metres (39 ft) wide, extending two stories. Its ornate features includes an abundance of gables and pinnacles, with many carved figures standing under a baldachin in carved niches, around a statue of Henry the Navigator, standing on a pedestal between the two doors.
The tympanum, above the double door, displays, in half-relief, two scenes from the life of Saint Jerome: on the left, the removal of the thorn from the lion's paw and, on the right, the saint's experience in the desert. In the spandrel between these scenes is the coat of arms of king Manuel I, while the archivolt and tympanum are covered in Manueline symbols and elements. The Madonna (Santa Maria de Belém) is on a pedestal on top of the archivolt, surmounted by the archangel Michael, while above the portal there is a cross of the Order of Christ. The portal is harmoniously flanked on each side by a large window with richly decorated mouldings.