From 1757, the Duke began construction of an enormous castellated mansion at Douglas. The architects of this, the final Douglas Castle, were the Adam Brothers (James Adam, John Adam, and Robert Adam). Had it been completed the castle would have been the largest in Scotland. As it was the Duke of Douglas died in 1761, and only around half of the original design was ever completed. The five storey building had round towers to the front and square towers to the rear facade, and stood in a very extensive park spanning the valley of the Douglas Water. The Duke's estate became the subject of a famous and bitter legal dispute, known as the "Douglas Cause", between his nephew Archibald James Edward Douglas and the Duke of Hamilton. Douglas was eventually victorious and ennobled as Baron Douglas in 1790, and the castle descended through his daughter, and granddaughter, to the Earls of Home. In the 1930s Charles Douglas-Home, 13th Earl of Home allowed the mining of coal in the park adjacent to the castle, in an attempt to relieve desperate levels of local unemployment. Sadly, the mining caused dangerous subsidence to the castle and it had to be demolished in 1938.