Model of a Penrose staircase
1968
1968
1960
1963
1963
1960s
1960
1961
1968
1964
1967
1966
1839 (original); circa 1988 (replica)
1960
1962
1967
(1962); 1982
1963
1964
1965
1960
1960
1990-96
1961
1965
1966
1964
1962
1960s
1966
1966
4000-2001 BCE
1962
2000-100 BCE
circa 1964
1965
1962
1960
1962
1967
1968
1960-1961
1961
circa 1966
1962-1967
1964
1967
1960s
1961
1967
circa 1965