Most of the seventeenth-century painters specialised in a certain theme, but Jan Baptist Weenix practised several genres simultaneously. He painted (group) portraits, still lifes, animal pieces and interiors, but also Italianate landscapes and port scenes. The Italianate paintings earned him the greatest acclaim. He is viewed as both inventive and versatile, and as the most skilled colourist of all Italianate painters.

Weenix returned from Italy in 1647. From that year on he signed his work, as with this painting, as 'Gio(vanni) Batt(ist)a Weenix'. It marks the start of a period in which he pursued more monumental compositions with figures on a grand scale. He frequently painted this type of port scene, composed of a foreground with figures and behind them the sea with ships and large buildings. He did not devise this type of composition, however, as similar scenes can be found in the work of the Antwerp painter Paulus Bril (1554-1626).

The monumental effect in this painting is created by the block-shaped building with tall colonnade at the back and the royal steps leading down to the port, flanked by the obelisk. The splendid sky completes the grandeur of the port scene. The painting is richly detailed without detracting from the overall harmony of the image. Freight is being loaded and offloaded along the broad stretch running along the waterside. Packed mules, horsemen and pedestrians weave their way through the throng. Further from the waterside, waiting soldiers are killing time playing cards. The harbour itself is crowded with lots of large and small sailing boats.

Weenix probably painted the statues depicted in the painting after his own sketches made in Rome, or after drawings made by others, circulated widely at the time.

At the top of the steps to the port we see the ‘Dioscuri’. These are found in Rome at the end of the Cordonata, the long sloping steps leading up to Piazza del Campidoglio. The Dioscuri (literally ‘Sons of Zeus’) are the twin brothers Castor and Pollux. They were known as two young valiant horsemen and as patrons of sailors. This make their position at the top of the entrance to the port very appropriate.