Bolsover castle is a Grade I listed ancient monument, built upon the grounds where two other castles once stood, dating back to medieval times. The current castle began construction in the 1600s, though was interrupted during the civil war where it fell into ruin. The castle as it stands was restored by Lord Cavendish by the time of his death in 1676.
Today Bolsover Castle is under the care of English Heritage and is frequently a host to a number of Dog-Friendly events on the castle grounds, and are famous for their medieval-themed knight's tournaments and jousts.
The grounds themselves are dog-friendly day-to-day, with the only restrictions being dogs aren't allowed inside any buildings such as the Little Castle, cafe or at the Cavalier Horsemanship displays. Though there are plenty of grounds and gardens to explore.