Motor racing began on the Isle of Man in 1904 with the Gordon Bennett Eliminating Trial and was originally restricted to touring automobiles. As the Motor Car Act 1903 placed a speed restriction of 20 mph on automobiles in the UK, Julian Orde, Secretary of the Automobile Car Club of Britain and Ireland approached the authorities in the Isle of Man for the permission to race automobiles on public roads. The Highways (Light Locomotive) Act 1904 gave permission in the Isle of Man for the 52.15 mile Highlands Course for the 1904 Gordon Bennett Eliminating Trial which was won by Clifford Earl (Napier) in 7 hours 26.5 minutes for 5 laps (255.5 miles) of the Highlands Course. The 1905 Gordon Bennett Trial was held on the 30th May 1905 and was again won by Clifford Earl driving a Napier automobile in 6 hours and 6 minutes for 6 laps of the Highland Course. This was followed in September 1905 with the first Isle of Man Tourist Trophy Race for racing automobiles, now known as the RAC Tourist Trophy and was won by John Napier (Arrol-Johnston) in 6 hours and 9 minutes at an average speed of 33.90 mph. The Manx Government brought in new legislation to enable the closing of public roads for motor racing and the Isle of Man was ready to take up the mantle of the Road Racing Capital of the World, a slogan it has used for many years.

The first motorcycle race held on the Island was the qualifying trials for the International race to be held in Austria. The course used ran from Quarter Bridge south to Castletown, then back through Foxdale to Ballacraine, then reverse way to the TT back to Quarter Bridge.

The first TT races where held on the triangular course with the start at St John's. The riders proceeded along to Ballacraine before turning left and following the current TT course through to Kirk Michael. At Douglas Road Corner in Kirk Michael, the short course left the current TT course and followed the coast road to Peel, before turning left again and heading back to St John's. In 1907 two races were held on the short course with H. Rem Fowler winning the twin cylinder class on a Peugeot-engined Norton at 36.22mph and Charlie Collier the single cylinder class on a Matchless at 38.22mph. They each set the fastest lap in their respective classes, Fowler at 42.91 mph and Collier at 41.81 mph. The short course was used for the first 4 years and in 1910 Charlie Collier won the last TT on the short course on a Matchless at 50.63mph. The fastest lap that year was by H Bowen on a BAT at 53.15 mph. In 1911 the racing moved to the Mountain circuit, which is used today.

The Mountain circuit is some 37.73 miles long and runs from the start at Glencrutchery Road in a westerly direction through Braddan, Union Mills, Glen Vine and Crosby until it reaches Ballacraine. At Ballacraine the riders turn right and head north through Glen Helen, Kirk Michael, Ballaugh and Sulby to Ramsey, some 23.5 miles from the start. Now the riders swing south and head up the daunting Mountain climb rising from sea level in Ramsey to some 1400ft at the highest point at Brandywell.

On the way they pass through Ramsey Hairpin, The Waterworks, Gooseneck, Guthries Memorial, The East Mountain Gate, Black Hut, The Verandah and the Bungalow. After Brandywell it is nearly all downhill to the finish, some six miles away, through Windy Corner and the 33rd Milestone on through Keppel Gate and the fast run down to Creg-ny-Baa. Then it's on down to Brandish and on up through Hillberry to Signpost Corner. Now just over a mile from the finish the riders swoop through Bedstead corner and the Nook and past the Governors residence on their left to Governors Bridge, from there it's just a short run up Glencrutchery Road to the finish line.

The TT mountain circuit is without doubt the greatest challenge any racing motorcyclist can take on, but it is not for the faint hearted. Each year some 500+ riders arrive on Mona's Isle to take on the gruelling mountain circuit in either the TT races in June or the Manx Grand Prix races in late August and early September. Most come just to pit there skills against the circuit with no thoughts of ultimate victory but just to gain a finishers award or a coveted replica. It is a dangerous circuit, but they all know the risks. No one is forced to race here, they all come for one reason and one reason only, to pitch themselves against the greatest pure road race circuit of them all, the TT Mountain Circuit, The Road Racing Capital of the World.