Tourism bosses are predicting an increase in visitors to Lincoln thanks to the castle's starring role in Downton Abbey.
Millions of viewers saw Lincoln Castle make its debut in the hit television series on September 16.
Its old jail stood in for York Prison, where the character John Bates is serving time for the murder of his former wife.
Filming took place in May, when the Echo published exclusive pictures of the production.
Emma Tatlow, manager of the Visit Lincoln Partnership, said: "We are expecting people to become more interested as it becomes more widely known that Lincoln was used.
"Past experience of things such as filming for The Da Vinci Code brought huge benefits to the area.
"Places like Oxford maximise on set locations used through special tours, so there may be a new business opportunity out there too."
District manager of the castle Will Mason said: "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."
The castle is set to feature in several episodes of the new series.
Downton Abbey airs on ITV on Sunday evening at 9pm.