Which Grade I listed building in Dorset, England was designed by the same designer as Blenheim Palace and Castle Howard? 
Eastbury Park: Eastbury Park was a country estate near Tarrant Gunville in Dorset, England. Eastbury Park:  The mansion has not survived, but its former service wing has become a country house known as Eastbury House, a Grade I listed building. John Vanbrugh: Sir John Vanbrugh ( ; 24 January 1664 (baptised) – 26 March 1726) was an English architect and dramatist, perhaps best known as the designer of Blenheim Palace and Castle Howard.
i don't know