A short documentary by Manoel de Oliveira. Quality is not great, but still watchable.
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From: https://archive.sensesofcinema.com/contents/03/28/de_oliveira.html

"Oliveira's first film, the 21-minute Douro, Faina Fluvial (“Labor on the Douro”), made at the moment of transition between silent and sound cinema, deals with diverse work-related activities taking place in and alongside the Douro River in Oliveira's native city Porto, in northern Portugal. Douro is not, however, a traditional documentary about the river and the city – it is much closer to the work of Walter Ruttmann, Dziga Vertov and the early Joris Ivens. Antoine de Baecque characterises the film as a “visual symphony”, and José de Matos-Cruz has referred to it as a “geographical mosaic” in which the director brings together a multiplicity of images – often shot from strikingly unusual angles or reflected in the water – of people, boats, trains, barges, bridges, houses, alleyways, ships, light and shadows, crashing waves, objects blowing in the wind and, above all, the river (de Baecque and Parsi, 12; Matos-Cruz 1996, 73). 

According to the director, Douro was inspired by an image he had seen in another film: the taut chain of an anchored boat resisting the strong currents of a river. The image's power and beauty reminded him of the banks of the Douro, with its intense activity of boats arriving and departing, loading and unloading merchandise (“Manoel de Oliveira: Entrevista,” 67). Oliveira apparently had little interest in documentary until he saw Ruttmann's Berlin: Die Sinfonie der Großstadt (Berlin: Symphony of a Great City, 1927), which he has referred to as “the most useful lesson in film technique” that he had ever seen. At the same time, he found Ruttmann's film rather cold and mechanical, lacking in a humanity that later films by the German director possessed. It was the humanity that existed along the Douro that Oliveira was interested in revealing (68; de Baecque and Parsi, 95). 

In an extensive interview granted to Antoine de Baecque and Jacques Parsi, Manoel de Oliveira refers to Douro as an experiment with cinematic specificity, the multiplicity of perspectives, and with the montage theories that were circulating at the time (96). The film is an exercise in light, shadows, rhythm, and changing camera-angles, evoking the urban transformations provoked by the inexorable process of modernisation. The key dramatic sequence, in which an ox-cart knocks a man down, is provoked when the driver of a car, distracted by an airplane flying overhead, backs into the cart, causing the ox to panic. This sequence, one of several fictional moments in the documentary, offers an early indication of the kind of cinematic hybridity that would later characterise much of Oliveira's work."
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18min
Black & White
Silent, no intertitles (Portugese titles)