It is located next to the Tagus River, is a square in downtown Lisbon, located in the parish of Santa Maria Maior, municipality and district of Lisbon, central Portugal
 
The area that was the site of the palace of the kings of Portugal for around two centuries and that today is partially occupied by some government departments, one of the largest squares in Europe with around 36,000 m 2 (180m x 200m), the square is limited by 79 arches.

Praça do Comércio is considered a historical symbol of political power and a manifestation of capital in Portugal, generally associated with state centralism.

In the year 1511, King Manuel I transferred his residence from Castelo de São Jorge to this location next to the river, and the Paço da Ribeira and its library of 70,000 volumes were destroyed by the 1755 earthquake.

The reconstruction of the square was coordinated by Eugénio dos Santos and became the fundamental element of the Marquês de Pombal's plan.

The buildings surrounding the square were used by different ministries and other public institutions for decades.

Today its use is divided between government departments, cultural and promotional activities, hotels, restaurants and cafes.

In one of the square's buildings is the famous Martinho da Arcada café, the oldest in Lisbon, and one of Fernando Pessoa's favorites.

After the 1910 Revolution, the buildings were painted pink but recently returned to their original color, yellow, the south side, with its two square towers, faces the Tagus.

The place was for a long time the noble entrance to Lisbon and, on the marble steps of Cais das Colunas, coming from the river, heads of state and other prominent figures disembarked and were received.

In the center of the square you can see the equestrian statue D. José, erected in 1775 by Joaquim Machado de Castro, the main Portuguese sculptor of the 18th century.

On the north side of the square, there is the Rua Augusta Triumphal Arch, the entrance to Baixa.

The area served as a car park until the 1990s, but today this vast space is used for cultural events and shows.

Some important historical events took place in this Square, such as: on December 1, 1640, the old square saw the end of the Iberian Union with the arrest of the Duchess of Mantua, and the death of Secretary of State Miguel de Vasconcelos, who was thrown from a palace window into the Terreiro.

In the earthquake of 1755, where the buildings that make up Terreiro do Paço are located today, there was the Royal Palace in whose library 70 thousand volumes and hundreds of works of art were kept, including paintings by Titian, Rubens and Correggio.

The precious Royal Archive with documents relating to oceanic exploration, including numerous letters from the discovery of Brazil and other ancient documents, were also lost.

On February 1, 1908, King D. Carlos and his son Prince Real D. Luís Filipe were killed when they were passing through the square.

During the 1910 Revolution, the square saw the Navy disembark at Cais das Colunas to occupy strategic locations in the city.

On October 5, 1910, in Praça do Município next to the yard, the Republic was proclaimed.

On February 18, 1957, Queen Elizabeth II of the United Kingdom disembarked at Cais das Colunas, on her visit to Portugal.

During the Estado Novo regime, some of the speeches by Council President Oliveira Salazar were given at the ministries' windows, namely on August 27, 1963, in a grand demonstration of support for Portuguese overseas policy.

On April 25, 1974, the square witnessed one of the episodes of the revolution that overthrew the government of Marcello Caetano and the Estado Novo.

On May 11, 2010, Pope Benedict XVI celebrated the Eucharist in the square for around 280 thousand people.

In 2016, the square once again hosted the Camões and Communities Day of Portugal celebrations, which had not been held here since the end of the Estado Novo.