List of largest optical telescopes in the British Isles

List of largest optical telescopes in Ireland and the United Kingdom is a list of the largest optical telescopes in the British Isles, including in the United Kingdom and Ireland.

In the 20th century many older telescopes are popular tourist attractions, such as at Royal Observatory in Greenwich, London.

The largest optical telescope in Britain was the Isaac Newton Telescope which had a 98 inches (2.5 m) mirror; it was located at the Royal Greenwich Observatory, Herstmonceux from 1965 to 1980, but was then relocated to Roque de los Muchachos Observatory on La Palma, Canary Islands.

The following is a non-comprehensive list of optical telescopes currently located in the British Isles with an aperture of 24 inches or greater: (61.0 cm) A noted accomplishment of the biggest telescope at the time, Ross's "six foot" leviathan, was the observation of the spiral structure of M51, which was presented at Cambridge in the summer of 1845.

[23] Herschel was quite prolific discovering a planet and many moons of the Solar system also with his reflectors.

The 28-inch Grubb refractor's dome at Greenwich.
Discovered as Georgium Sidus , later known as Uranus was one of the famous discoveries made from the British Isles
The mirror from the 40-foot telescope , on display at the Science Museum , London.
Former Royal Greenwich Observatory, Herstmonceux , East Sussex; this was an important site for telescopes in the latter 20th century in England.
Closeup of lower end of a 28-inch aperture telescope
The old INT dome