Model of a Penrose staircase
1968
1968
1967
1967
1839 (original); circa 1988 (replica)
1967
(1962); 1982
1990-96
1966
1966
1903 (original); 1982 (model)
1966
2000-100 BCE
4000-2001 BCE
1968
circa 1966
1967
1967
1968
1966
1968
1968
1968
1968
1968
1968
1968
1968
1968
1968
1968
1968
1968
1967
circa 1966
1980-1950
1966
1968
1966
1966
1968
1968
1967
1968
1966
1966
1990-95
1966
1966-1968
1830 (original); 1967 (model)
before 1966