Four finalists have been chosen from a mix of architectural practices, including international heavyweight BDP, conservation expert Purcell Miller Tritton, and Long and Kentish in association with Colin St John Wilson.
One of two entries by Purcell Miller Tritton is a £19 million transformation of Weston Park Museum, part of Sheffield's Galleries and Museum Trust, which was created with the help of the local community.
The practice's second entry is a treatment of George III's country retreat Kew Palace, which has been fully restored and recreated for visitors.
The final firm up for the £100,000 prize is Long and Kentish for Pallant House, home of one of the best collections of Modern British art, which had an £8.6 million extension created and designed with Colin St John Wilson.
The winner of the coveted prize will be announced on 24 May at the RIBA headquarters in London.