Powell and Moya's Blue Boar Quad at Christ Church, Oxford University, has won Grade II-listed status.
Heritage minister Andrew McIntosh singled out the college residence, completed in 1968, as one of the finest buildings to emerge from university expansion in the 1960s.
'Blue Board Quad is recognised as one of the earliest, most substantial and least altered post-war university buildings by arguably the leading specialist in the country,' added McIntosh.
Built adjoining the narrow high-walled Blue Boar Street, Powell and Moya's scheme forms a staggered, extended U-shape comprising 61 flats and eight penthouses.
The penthouses are arranged as a broken, set-back series of horizontal planes, which, says the Department for Culture, Media and Sport, reduce the scale of the development seen from the street but add to Oxford's historic skyline.
Much of the building is on four storeys, except the extreme western section that has three floors and a semi-basement.
Philip Powell and Hidalgo Moya are renowned for inserting good modern architecture, featuring traditional materials and elegant proportions, into historic college settings at Oxford and Cambridge.
This is endorsed by Nikolaus Pevsner and Jennifer Sherwood, editors of 'The Buildings of England: Oxfordshire', who write: 'Powell and Moya are by now recognisable, not only by motifs but by their approach. The range is clearly a number of identical units, but they are strung up so intelligently that no uniformity appears- May these outstanding architects never succumb to fashion.'by Clive Walker