The Solfatara of Pozzuoli, near Naples, is an extraordinary place - a volcanic crater characterized by its sulphurous soil. As the shallow crater is also filled with underground water, jets of steam pierce the fragile crust of earth while the ground seems to move, tremble and almost boil, and hot mud often comes to the surface bubbling over. The area is permeated by the strong smell of sulphur. It looks, and feels, like the gates of Hades.
Detail from Solfatara, engraving by Johannes Stradanus (1523-1605), printed by Philip Galle.
The first engraving above, from an original by Mercati, has remained long unknown but until it was rediscovered in the 1700s and copied as one of the plates of Diderot and D'Alembert's Encyclopedie. The beauty of the composition relies on the circular shape of the crater which, in reality, has a more irregular and elongated shape. The Stradanus engraving (detail above - full picture follows), on the other hand, puts less emphasis on the composition and on the crater itself, but is rich in dramatic detail.
Solfatara, engraving by Johannes Stradanus (1523-105), printed by Philip Galle.
Stradanus here is particularly successful at depicting the light, yellowed-out tone of the dirt at the centre of the crater, and its quality - sandy at the top, and moving, almost fluid or liquid just below. He also situates the solfatara in its context, which is actually rather urban. What we see in the picture is probably the town of Pozzuoli and its gulf, looking north-west towards Capo Miseno (top left in the picture). In the image below you can see a detail of Pozzuoli itself.
Detail from Solfatara, engraving by Johannes Stradanus (1523-105), printed by Philip Galle.
And here's a map just to situate the view in a context. The area you're seeing is basically the northern end of the bay of Naples which is bookended by the Vesuvius to the south.
Since antiquity the solfatara has been described as the entrance to the underworld, or to hell. To visit it means to realize that the ground we're on is anything but solid - it is, in fact, an ever-changing subterranean landscape of currents, shifting lava, boiling muds, liquid rock, vaporized water, stinky steam, and more.
Solfatara, copper engraving, 1707. From Les delices de L'Italie (Paris: De Rogissart, 1707).