'View from the Window at Le Gras' is the oldest known what?

View from the Window at Le Gras is a heliographic image and the oldest surviving camera photograph. It was created by Nicéphore Niépce in 1826 or 1827 at Saint-Loup-de-Varennes, France, and shows parts of the buildings and surrounding countryside of his estate, Le Gras, as seen from a high window.

Niépce captured the scene with a camera obscura focused onto a 16.2 cm × 20.2 cm (6.4 in × 8.0 in) pewter plate thinly coated with Bitumen of Judea, a naturally occurring asphalt. The bitumen hardened in the brightly lit areas, but in the dimly lit areas it remained soluble and could be washed away with a mixture of oil of lavender and white petroleum. A very long exposure in the camera was required. Sunlight strikes the buildings on opposite sides, suggesting an exposure that lasted about eight hours, which has become the traditional estimate. A researcher who studied Niépce's notes and recreated his processes found that the exposure must have continued for several days.