The painting illustrates the Porta Portella, the main entrance into the city of Padua from the east for those arriving from Venice. Canaletto has set it slightly off centre to the left and seen from the side. Originally known as the Porta Ognissanti (All Saints' Entrance), it was built to a design by the architect Guglielmo de'Grigi, nicknamed Bergamasco. Located on the crossroads of the present-day Via Portello (known as the Via Venezia on the other side of the Piovego Canal, a tributary of the Bacchiglione river) and the Via Gradenigo, which changes its name to Loredan along the stretch that enters the city and runs towards the Eremitani. The gateway, which is now in a reasonable state of preservation, although the lantern has lost its dome, is now known as the Porta Venezia.
Of the various buildings depicted here, unfortunately the most important ones have not been identified -assuming they are not inventions of the artist- such as the building with the colonnade on the other side of the canal, set slightly back due to the bridge, while in the background the Church of the Carmini can be seen. But it should be said that Canaletto was not accurate in his reproduction of this part of Padua on canvas, since, among others things, the corner of wall in the foreground is imaginary and the Portello Bridge had three instead of two pilasters (although, as Fern Rusk Shapley has observed, the third could be "concealed from our view by the left bank of the canal"). In addition, the artist, in his over-zealous passion for ruins, has shown the wall in the foreground in a rather more decayed condition than really was the case. Canaletto's liberty in topographical matters has been well researched by André Corboz. For a useful comparison between the present condition of the gate and Canaletto's freely manipulated version, the engraving of 1831 by Pietro Chevalier offers an intermediate, analytical view. A second version of this view of Padua which is very similar and of almost identical dimensions has been a part of the Samuel H. Kress Collection since 1964. The Kress painting is, in fact, very similar with regard to the viewpoint used and the elements included, and both can be regarded as more or less the same.
Both versions of the Porta Portello have been dated more or less unanimously to the early 1740s. This dating is justified by a trip to Padua made by Canaletto with his nephew Bellotto in 1740 or 1741. Both paintings share the dark tonality, luminous atmosphere and an almost poetic mood with a third painting of the Dolo sur Brenta (Washington, Private Collection), qualities which induced Pallucchini to see in it "a serenity already worthy of a Corot." The journey to Padua is documented by preparatory drawings which still exist, even for the view of the Porta Portello (Vienna, Albertina; Windsor, Royal Collections, Windsor Castle; New York, The Metropolitan Museum of Art; Darmstadt, Hessisches Landesmuseum). This makes it more difficult to date the canvases, which are clearly based on drawings and "constructed" in the studio. Links had already dated the paintings twenty years later to around 1760 while recently a new element has emerged in connection with the above mentioned View of Dolo: a label on the back of the canvas with an inscription in 18th-century handwriting reading "Antonio Canaleto [sic.] / 1754"suggests that there was a pre-existing signature on the back of the canvas. A similar dating would also explain the palette of grey and green tones and the use of older graphic prototypes, both common aspects of late works of Canaletto's English period.
It would appear to be the case that the artist was not particularly interested in the Porta Portello, which he includes in the composition without making it the presiding element. Rather, "the relatively tranquil ambient of the outskirts of a mainland town, and the crumbling masonry of the wall in the foreground captured his attention as much as anything", albeit with numerous elements added by the artist himself from his own repertoire.