Creg-ny-Baa (English: /ˌkrɛɡnəˈbɑː/, Manx: [ˈkʰɾɛɡ nə ˈbɛ]; 'rock of the cow')[1] is located between the 3rd Milestone and 4th Milestone of the primary A18 Snaefell Mountain Road and the road junction with the secondary B12 'Creg-ny-Baa Back-Road',[2] in the parish of Kirk Onchan in the Isle of Man.

[6] The area is also the site of a radio and telecommunications station built in 1939 for the UK General Post Office near to the Creg-ny-Baa road junction.

[9] In 1911 the Four Inch Course was first used by the Auto-Cycling Union for the Isle of Man TT motorcycle races.

[10] This included the Creg-ny-Baa section[11] and the course later became known as the 37.73 mile Isle of Man TT Mountain Course for motor-cycle racing which has been used since 1911 for the Isle of Man TT and from 1923 for the Manx Grand Prix races.

[12] To enable motor-cycle and sidecar racing on the new Clypse Course for the 1954 Isle of Man TT Races, during the winter of 1953–54 road widening and re-profiling occurred on the TT Course at the Creg-ny-Baa road junction along with nearby Signpost Corner, Cronk-ny-Mona and the approach to Governor's Bridge by the Isle of Man Highway and Transport Board.