The Aliados Avenue is an important street layout in Santo Ildefonso parish, in downtown of Porto in Portugal. With the Freedom Square and the General Humberto Delgado Square is a continuous urban fabric. It is the main avenue and the city center of Porto. Avenue honors the Allied countries of the First World War. The Avenue construction project kicked off on 1 February 1916. At the site there was a set of short streets and alleys which they called “the washtubs.” Furthermore, it had two main streets very busy, parallel, between the corner Sampaio Bruno and off the Trinity: the street Pedro and the Orangery.
The launching ceremony of the project, the February 1, 1916, was attended by the then President of the Republic, Bernardino Machado, and was the dismantling of the “first stone” of the baroque palace of Liberty Square, where, since 1816 and until then, was installed the Chamber of Porto.
It was precisely on this day that was approved by city council meeting the construction project of the current building of the Town Hall just above the Allies as part of the expansion plan of the city’s Civic Center designed by the English architect Barry Parker.
The statue “Youth”, the sculptor Henrique Moreira was installed in 1929.
The magnificence of its architectural complex and its central character make it the “living room” of the city, place par excellence where portuenses focus to celebrate special moments.
All the buildings are of good granite, many of them crowned with skylights, domes and spiers. The axis of the avenue is marked by a wide central board which, by mid-2006, was landscaped and is now completely paved by parallelepiped granite.
Midway through the avenue, on either side are the two mouths of the Allied D Line Port Metro Station. the construction of the station was precisely what led to the complete redesign of the avenue,  work that was given to architects Álvaro Siza Vieira and Eduardo Souto Moura. The project was surrounded by a huge challenge  for allegedly misrepresenting the historical and landscape tradition of the place. After all, the work – which sought to create a continuity between the avenue and the square of Freedom – was, in general terms, realized.
On the afternoon of May 15, 1982, Pope John Paul II presided at a Mass celebrated by the City Hall, the Avenida dos Aliados, in his first apostolic visit to Portugal. 
At the top, where stands the City Hall of Porto, the promenade gives way to the General Humberto Delgado Square.