A toll bridge home that offers the owners a tax free income has been put up for sale.
The Whitney-on-Wye bridge in Herefordshire was built in 1797 by an Act of Parliament that also exempts the toll income from tax.
The current owners, Grahame Penny and Maggie Taylor, are selling up after three and a half years at the helm.
The landmark, between Hereford and Hay-on-Wye, is one of just eight privately owned toll bridges in the UK which is exempt from tax and brings in an income of around £100,000 a year.
It has received more than its fair share of fame over the last few years - featuring on The One Show, Secret Britain and Tim Wonnacott's Antiques Roadtrip.
"We bought the business when it was struggling during the downturn and have been working 24/7 to build it back up," Ms Taylor said.
"We regard ourselves as custodians of an ancient monument rather than owners, and have concentrated our efforts on the land around the toll bridge to create year round support to keep the business going."
The couple have diversified to include game and coarse fishing, canoeing on the River Wye, alongside camping and a cafe.
"We have now reached the stage where we have done all the hard graft developing the business and are ready to hand over to a new owner to maintain it," she said.
"We have had to overcome a great many problems along the way and are now looking forward to a holiday."
The toll bridge is on the market with Colliers International for £850,000 freehold and comes with a two-bedroom toll cottage and just under two acres of land.
Peter Brunt, hotels director at the agency, said: "I have been invited to sell pubs, hotels and even a vineyard, but have never been asked to sell a toll bridge before.
"Despite being nearly 240 years old, the bridge has had just four owners - with one family holding onto it for 180 years. So this really is a once in a lifetime opportunity for someone."
Mr Penny and Ms Taylor have already been granted planning permission to build a new house, toilet block, visitor centre and four self-catering lodges.
"This is a once-in-a-lifetime opportunity for someone to fulfil a lifelong ambition to secure an income while building a new life by the river," Mr Brunt said.
The toll bridge uses an automatic barrier and charges cars £1 per journey, with an operating profit of £56,396 forecast. For a higher-rate tax payer it would be £93,000 as no income tax is paid.