Originally designed as a bell tower, the building ultimately transformed into elaborate arch within more than century-long delays.
Because of the top cornice's great height (over 100 feet (30 m)), the figures above it had to be made colossal. The female allegory of Glory, which is dressed in peplos and measures 23 feet (7.0 m), stands on a three-step throne and holds two crowns. The Valor is personified by an amazon, partially covered with chlamys and wearing a high-crested helmet with dragon patterns, which were the symbols of the House of Braganza. The Valor's right hand holds the parazonium, with a trophy of flags behind. The Genius encompasses a statue of Jupiter in his left hand. At his right side are the attributes of writing and arts.
The four statues over the columns, made by Victor Bastos, represent Nuno Alvares Pereira and Sebastião José de Carvalho e Melo, Marquis of Pombal on the right, and Vasco da Gama and Viriatus on the left. The two recumbent figures represent the rivers Tagus and Douro.