Before the TV series launched, a few hundred tourists turned up daily when the castle was open to the public; now up to 1,300 guests a day pass through the heavy doors.
The Saloon is the heart Highclere Castle, just as it is on Downton Abbey.
The State Dining room was transformed by Sir Charles Barry into the Stuart Revival style of interior decoration.
The Library of Highclere Castle, designed by Thomas Allom, who took over the completion of the Castle on the death of Sir Charles Barry.Paul Grover
Lady Fiona Carnarvon is the current chatelaine of Highclere Castle.Paul Grover / Rex Features