Nappa Hall beckons you to change your life, to give up your day job and devote time and energy to restoring one of the finest fortified manor houses in England. The price makes it even more tempting: £500,000. Although one tower has not been occupied for 40 years, the other, with a gabled cottage beside it, was tenanted as recently as last month.

The setting of Nappa Hall, near Leyburn in North Yorkshire, is intoxicating. On a sunny summer day it is hard to imagine a grander view. The drive along Wensleydale takes you past mighty Bolton Castle, visible for miles around. Nappa, built in the 1450s, is Bolton's little brother, with twin towers and battlements and great hall between.

Like Bolton, it commands a breathtaking panorama along and across the dale, with stone-walled fields descending to the river and the noble outline of the fell rising on the far side. Better still, the passing road is out of sight and hearing. You enter through a carriage arch in a stable range into a courtyard open on the south. To the left is a four-storey tower with battlements, very much like the Pele towers in Northumberland, built as a protection against raiders from Scotland. The tower is built of rugged stone that can clearly endure for 1,000 years. The masonry detail is delicious, too, with medieval stone mullioned windows diminishing in size from floor to floor.

Beside the tower, the medieval great hall retains the original window tracery; the deep porch has a broad pointed archway. Beyond is a second battlemented tower, from which extends a cottage-like gabled wing with sash windows on the upper floor.

The white front door in the gabled wing is inset with diamond-shaped studs. It leads to a stone-flagged kitchen and ancient sculleries facing south, so there will always be a good view while washing up. The ceilings in this part on the house are low but on the first floor are handsomely panelled rooms, of early 18th-century date, with stone fireplaces. There is also a pretty Georgian cantilevered staircase rising in a graceful curve with stone steps projecting from the walls.

The challenge becomes apparent in the great hall, an impressive 29ft wide and 40ft long. Huge paving stones cover the floor but walls and ceilings are bare and stained with damp. The big question is whether a splendid medieval timber truss roof is waiting to be revealed above.

Ceilings and floors are rotten in the western tower, and I was not even allowed to ascend the stone spiral stair to the first floor. Yet the chance is here to create an impressively proportioned room on each level, with views growing ever more breathtaking, and this can be done while you live in the east wing. The thrill will be to work with the original, largely untouched medieval masonry.

Nappa was built by James Metcalfe, who fought at Agincourt. Interestingly, it has always passed by inheritance; William Metcalfe, whose family farms the surrounding land, is now selling the house, recognising that it needs major repairs. The house comes with just five acres but a further 90 acres are available by negotiation, including a recently restored laithe barn, field barns and an extensive river frontage. Winters will be cold but the snow-clad fells will be a majestic sight.

Fast facts

What you get: Grade I listed house with great hall, six bedrooms in five acres with stone outbuildings. In all, 8,000 sq ft. Where is it: Leyburn 12m; A1 at Bedale 25m. Trains to London from Darlington and Northallerton take from 2hrs 23min.

Price: £500,000 via Carter Jonas, 01423 523423.

Times recommends

• Second homes: credit crunch casualty or money-spinner?
• How I built my own sliding house
• Top 10 incentives for house buyers