'Belvedere' by M.C. Escher (1958)
The man sitting at the bench is holding an impossible Necker cube. The bars in the window to his left are geometrically valid but practically impossible to assemble. The woman near the stairs is modeled after a figure from Jeroen Bosch’s triptych The Garden of Earthly Delights.
A small part of the right panel of Jeroen Bosch's The Garden of Earthly Delights (1481-1490, Museum Prado Madrid)
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