Plas Machynlleth

It was brought into the family following the 1846 marriage of the then Viscount Seaham (who later became, in March 1854, Earl Vane, and in November 1872, the 5th Marquess of Londonderry) to Mary Cornelia Edwards, who inherited it on the death of her father, Sir John Edwards, in 1850.

After Lord Herbert was killed in the Abermule train collision on 26 January 1921,[2] no family members lived there.

After the Second World War, the 7th Marquess of Londonderry, a prominent Ulster Unionist politician, gave the mansion and its estate to the town.

The oldest parts of the house date to the seventeenth century; the main entrance front was added in 1853.

In 1995, after a £3 million refurbishment, funded by Montgomeryshire District Council and the European Union, the building became the 'Celtica' heritage centre.