Lincoln Castle made an appearance in popular TV series Downton Abbey on Sunday, September 16.
The programme returned to screens for its third series and the first episode is now available on ITV Player.
The castle stood in for York Prison, where John Bates is serving time for the murder of his former wife. The filming took place in May.
The castle is set to feature in several episodes of the new series.
District Manager Will Mason said: “It’s a real privilege to have been selected as a filming location for such a hugely popular television series.
“Lincoln Castle and its prison are such unique, special places and it’s great to be part of a show that’s seen by millions of people around the globe.
“The filming took place in May, but we’ve had to keep quiet about it until the programme was aired. Now the secret’s out, I’m sure we’ll have extra visitors to the castle.
“The crew even left us a few props, which we’ll be showing off. We’re all looking forward to watching the fate of Mr Bates and Anna.”