Among the highlights are four rooms with dozens of oil studies painted on the outside by the pioneers of outdoor painting in the late 1700s and early 1800. most of these artists were northern Europeans who flocked to Italy to heat and light golden. 
This is a stormy landscape near Rome, circa 1800, painted by Simon Denis (1755-1813). He worked quickly to capture a fleeting rainbow effect in heaven. His work preceded the era of photography, the Impressionists, the Hudson River School, and even Constable and Corot.
Denis painted four decades before the invention of collapsible paint tubes. He was to be his grind pigments on site or transporting paints prepared in pig bladders obtained from the butcher.
This is a view of the Quirinale in Rome, 1800, also by Denis. He carefully made the distant city and the center of the roof. I guess it worked at the sight of his hotel window, and he ran out of time. 
The right lane is unfinished, which outlines his method. It blocked in large aircraft first and probably intended to add windows and other details later.
Antoine Xavier Gabriel de Gazeau (French, 1801-1881), painted it on the spot study of the door of the temple of Luxor in 1836. Drifting sand covers collossal digit height chest.
at the top of the building to the right, you can see its transparent block in the lower half of the wall essentially covered by a second semi-opaque layer. I could say that it was painted in two sessions of two hours each.
These paintings seem to have been painted yesterday. One of the remarkable qualities of full working air is that it escapes the classic formulas of his time to the artist. It takes all the fiber concentration to capture what you see when you are face to face with nature. All product formulas go out the window.
The Metropolitan Museum has brought many other realistic paintings back in the light, giving a much more balanced view of the 19th century painting. There are paintings by Gérôme, Repin, Leighton, Sorolla, Mucha, Bouguereau, and Bastien-Lepage. All rooms were packed and buzzing with energy and interest. Finally, the tide is turning. Thank you, Drue Heinz, Philippe de Montebello and Met curators!
Metropolitan Museum press release on new installations. Link.
New York Times coverage, Link.
Article by A. Malafronte on the history of outdoor paint, Link
Tomorrow: Bronze Weathering
