Jan van der Heyden, 'A View in Cologne', about 1660-5

This is one of at least four versions that Jan van der Heyden made of this scene of Cologne and its half-built medieval cathedral. Although he lived in Amsterdam he travelled quite widely, including visits to German cities along the Rhine such as this. The river was a vital trading route, and Cologne would have been familiar to many merchants in Amsterdam.

It is an alluring view. Van der Heyden has captured the lengthy shadows and raking light of a bright morning in the city street. The long perspective down what was known as Trankgasse is populated with people from all walks of life. We see strolling gentry, a maid carrying baskets, a horseman, a woman with children, and a beggar. These were added, on instruction, by the specialist painter Adriaen van de Velde.

The rest of the painting is certainly by van der Heyden. While he has taken extraordinary care to make the scene seem real – look at the way he has articulated the cobbles and the shadows falling across the brickwork – he has also let his imagination run free. Much has changed or been demolished in the 350 years since this scene was painted, but contemporary drawings and the variations in his own versions of the view tell us that van der Heyden made significant adjustments to what he saw.

Take the cathedral. When van der Heyden made this painting the building was certainly still the confusing jumble of unfinished parts we see here. The foundation stone of a hugely ambitious project had been laid in 1248, and the construction work had ground to a halt 300 years later. Work didn’t restart until the campaign of 1842–80 which finally completed the building. So we're looking at a project which had gone nowhere for a century. The strange contraption on top of the unfinished south-west tower is the original medieval crane. The shadowy stump just behind the line of trees is the north-west tower, intended as a twin to frame the west facade. Behind that is the choir, which would remain bricked up until the nave was finally completed two hundred years later. But while the layout of the building is correct, many of the details, such as the window traceries and the dimensions of the tower, are not.

Van der Heyden made similar changes to other buildings. The most prominent, with the walled garden and the bright red brick, is the deanery. This had just been extensively rebuilt, and although it no longer exists we know that the artist painted it in a broadly accurate way. However, the pinnacles on the stepped gable in the centre of the building seem to have been a product of his imagination. Other buildings, notably the two in the right foreground which are reminiscent of the style prevalent in Amsterdam at the time, appear to be entirely made up.

Why would van der Heyden take so much trouble to paint with such attention to tiny detail, and yet take such liberties? Most likely his concern was to produce a pleasing view which captured the sense of a place, rather than a precise record.