The Queen has visited the city to see the newly-completed Royal Papworth Hospital and the National Institute of Agricultural Botany.
Her Majesty then enjoyed lunch at Queens College.
At NIAB, which The Queen, 93, first visited in 1969 on the occasion of its 50th anniversary, she saw an exhibition marking a century of crop research and also saw the new building facilities.
At the conclusion of her visit The Queen planted a tree and unveiled a plaque to mark the visit in the NIAB's 100th year.
During her visit to Papworth, meanwhile, HM The Queen met patients and staff as well as being given a tour of some of the new facilities at the specialist heart and lung hospital which recently located from his historic home at Papworth to a state-of-the-art site at Addenbrookes.