The original Gateway of Avis is one of the oldest gateways of the medieval wall, being its first known record from the mid-fourteenth century. This old gate was sealed after 1806 and open again in 1967. The new gate was opened in 1804, as reads the inscription in marble on the outside.
In the clear span of the original bow there use to be life-size frescoes of St. Sebastian, St. Anthony, Our Lady of Espinheiro and the scene of the escape from Egypt, and underlying around 1482, according to tradition, was founded the chapel of Nossa Senhora do Ó, that suffered irreparable damage caused by the bombing of the city during the 1663 sieges. The church, was rebuilt in 1768 and improved in 1804 and features popular characteristics.