In the 1950s, Victor Palla and Manuel Costa, two architect friends, portrayed the city of Lisbon in more than 6,000 photographs. These were published in an eponymous book circulated in fascicles during the fascist regime, but forgotten for the next half-century. After their deaths, it became the photo book with the greatest international projection of all time and this film is a tribute to the work of these two figures, which is now 100 years old.