The countryside around the city of Rome has played a vital role in the history of landscape painting. For nearly a century, from the 1780s until the development of Impressionism, painting oil sketches in this area became a mandatory phase in the training of all good landscape painters in Europe. This weekend I show some of the best examples of these exercises undertaken early in the careers of some of the greatest artists of the nineteenth century, from Valenciennes who started it, to Corot and Böcklin.

It was the co-founders of landscape painting in Europe, Nicolas Poussin (1594-1665) and Claude Lorrain (c 1600-1682), who started painting the Roman Campagna, from about 1624 onwards. Although both were born in France, they spent almost their whole careers based in Rome, where they went out and sketched in front of the motif. They then used those studies to assemble composite idealised landscapes for their studio oil paintings, leaving little trace of their original sketches.

It was Claude Joseph Vernet (1714-1789), another pioneer French landscape artist who worked for many years in Rome, who first recommended to the young Pierre-Henri de Valenciennes (1750–1819) that he should follow this practice by painting oil sketches en plein air in the Campagna. In about 1782 Valenciennes started to amass his personal image library of sketches of the Roman countryside, and when he returned to France in 1785 he used those for his studio paintings.

One of the finest and the best-known of all Valenciennes’ oil sketches is this showing Farm-buildings at the Villa Farnese: the Two Poplar Trees reputedly from an earlier visit in 1780. This shows a Renaissance villa now in the centre of the city of Rome, although here its park setting makes it look as if it is out in the country. It was built in 1506-10 for a banker, and appropriately contains superb frescoes by Raphael and others. It is now owned by the state and most is open to visitors.

View of the Convent of Ara Coeli with Pines is a superb view of what’s known as the Basilica di Santa Maria in Aracoeli, again in central Rome. This is on the top of the Campidoglio, and affords the view over the city appearing behind the pine on the right. It’s situated close to the Forum.

This untitled sketch shows a different view over the city.

Several of these surviving oil sketches are brilliant studies in the effects of light, such as Rome: Houses and a Domed Church above.

I’m not sure if anyone has identified the buildings shown in Rooftops in the Shadows, but suspect that this too is close to the centre of Rome, perhaps on one of its hills. Is this the first plein air painting of washing on the line?

Around forty years later, John Constable sketched clouds and weather in what he called ‘skying’. Here’s one of Valenciennes’ groundbreaking sketches from the early 1780s, in Rome: Study of Clouds. He wasn’t the first plein air painter by any means, nor the first to make sky studies, but it was he who established the practice among landscape artists, both in his direct teaching and in his book published in 1800.

The Louvre has most of Valenciennes’ surviving oil sketches, but by no means all of them. This superb Italian Landscape is now in the Museum Boijmans Van Beuningen in Rotterdam, The Netherlands.

The National Gallery of Art in Washington, DC, has another of his sky sketches, this Study of Clouds over the Roman Campagna.

The Cleveland Museum of Art, in Ohio, has this magnificent View of Rome, which I think compares with the Villa Farnese above in its quality. Notable here is the depiction of the clouds of dust and smoke rising from the streets of the city, which surely qualify it as an ‘impression’.