The current Georgian house was started circa 1788 by Sir Robert Howell Vaughan and completed by his son in 1796 after his death in 1792. There was a house-warming celebration on January 1st 1797 with a set of glasses engraved for the event).

The current house is probably the fifth to stand on the site (or close proximity) of the earliest one. The house is built of dressed blocks of local dark grey stone, with the recessed parts having sandstone surrounds. It has a shallow pitched slate roof.
Part of the tower of the previous 17th century house is incorporated in the south-west corner and bricks from the 16th century house can still be seen inset into the back wall. Sir Clough Williams-Ellis (creator of Portmeirion, some twenty-five miles away) designed some alterations to Nannau in 1934, but I am unsure what these were or if they were implemented.

The Pavilion Wings (which can be seen on the two early postcards above and on the header photograph) were located behind the house and were added by Sir Robert Vaughan (2nd Baronet) in 1805-1806, from designs by the architect Joseph Bromfield (1744-1824) who also designed the new house at nearby Caerynwch in 1780 and is reputedly the architect of the main Nannau house, although this cannot be confirmed.
The wings were demolished in the late 1960s-1970, although the cellars seem to have survived, as do the arches of the east (right) wing and some of the outline of the buildings behind.

Behind the west (left) wing there used to be a kitchen which was built to celebrate the coming of age of Robert Williames Vaughan, 3rd Bart in 1824. To the rear of that is an old Smokehouse, including openings at the base of one wall to permit the entry of smoke and another utility building is next to that, both of these are in a good state. Also to the rear are the remains of an old squash court flooring.

There are also three ponds in the garden, which still survive, although they are now overgrown.
The house was listed Grade II* in 1952. It is important to point out that it is Grade II STAR and not just Grade II. This is a breakdown the percentage of graded buildings (although based on buildings in England, I think it is roughly the same in Wales):
Grade II – 92%
Grade II* – 5.5%
Grade I – 2.5%
Major-General John Vaughan describes Nannau in his war memoirs, “Cavalry and Sporting Memories”, published in 1954: “Nannau is about the best built Georgian house I have ever seen. With huge blocks of stone and round, pointed and projecting mortar. Incidentally, I cannot find out the composition of the cement but I have been told that it was burnt lime, fine river sand and bullocks’ blood or white of eggs. It is previous to Portland cement. All the stone was, of course, hand dressed and the interior woodwork and ceilings are a monument to the old Welsh craftsmen, who have now entirely ceased to exist”.
He describes the estate as “one of the most beautiful in the United Kingdom”…

“Nannau house is nearly 800 feet about sea level although tidal water is only three miles distant, so it rejoices in both mountain and sea air. In my youth it was an ideal place for anyone who could use a gun or fishing rod, with two rivers and two lakes, four small grouse moors and about 3000 rabbits a year in the Park, Warren and Home Farm, plus pheasants reared on the profits of the rabbits”.