 The 26th Milestone curve, situated on a steep up-hill section of the primary A18 Mountain Road, was part of the Highland Course and Four Inch Course used for the Gordon Bennett Trial and Tourist Trophy car races held between 1904 and 1911.The 26th Milestone is part of the Snaefell Mountain Course used since 1911 for the TT and Manx Grand Prix races.The A18 Snaefell Mountain Road was developed in the mid-19th century from a number of pre-existing roads and bridle paths.