ArtLex
Art Lex: Landscape
A very nice website with a definition of landscape and several examples of landscape paintings and photographs. Provides links to landscape art from specific historical eras.
ArtLex
Art Lex: Landscapes by Artists Born Between 1801 and 1820
Great website of landscapes done by artists born in the early 19th century (before 1820). Includes nice images and links to further information on specific pieces of art.