The Torchwood Institute (usually referred to simply as Torchwood) is a 'secret' organisation based in the British Commonwealth. It was founded by Queen Victoria to research and combat alien threats to the British Empire.

1879: The organisation was created by Queen Victoria after an incident at Torchwood House (the House is donated to the Crown).
1880: Hubs are built in London, Glasgow, Edinburgh, Dublin, Belfast, Galway, Cardiff, Plymouth, Dinnet, Birmingham, Liverpool, Hull and Newcastle-Upon-Tyne as well as all over the British Empire.
1882: Started collecting alien technology.
1885: London, Dinnet and Edinburgh Hubs open for business.
1888: The agency becomes secret.
1897: The Cardiff and Glasgow Hubs open for business.
1898: Every other Hub opens for business.
1899: Jack Harkness joins Torchwood Cardiff as a freelance agent.
1900: The Forge is created, a sister agency of Torchwood designed to forge superweapons to protect the Empire.
1902: Torchwood’s forward policies are shown for the first time as a black man, Charles Gaskell, is appointed leader of Torchwood Cardiff.
1903: Underground railway tunnels between the London, Cardiff and Glasgow Hubs are completed.
1906: A mysterious “earthquake” hits the Bristol Channel. It caused great damage to the Cardiff Hub, so it is redesigned to be sturdier. The other Hubs are rebuilt in a similar way.
1914: Due to worries about spies infiltrating Torchwood, self destruct mechanisms are installed in every Torchwood base (explosives and/or a flooding system).
1922: Dublin and Galway Hubs are decommissioned during the Irish Civil War.
1923: Jack Harkness acquires evidence of aliens at Pompeii.
1924: Edinburgh Hub is decommissioned.
1932: Torchwood Belfast disappears (the Hub and everyone in it)
1940: The organisation is merged with the Royal Reconnaissance Service.
1941: The first prototype of the Rift Manipulator is developed by Alan Turing.
1942: Torchwood Belfast reappears.
1953: Has become so influential the London police are scared of it.
After a disastrous attempt by the Forge to open a spacetime Rift, the government takes direct control of its operations.
1958: Emergency Hubs are built into the Hubs in Britain in case of a nuclear war.
1967: UNIT is formed. Torchwood is secretly given control of UNIT UK, so it can take alien technology from the organisation and put it in the Glasshouse, a Torchwood research facility.
1973: Hub is constructed in Milton Keynes.
1981: Torchwood House opens to the public.
1983: Bought the company HC Clements.
1990: The numeral system officially implemented in the names of the branches (Zero: Dinnet, One: London, Two: Glasgow, Three: Cardiff, Four: Belfast, Five: Birmingham, Six: Liverpool, Seven: Hull, Eight: Newcastle-Upon-Tyne, Nine: Cornwall, Ten: Milton Keynes, the rest of the numbers were assigned to overseas Hubs.)
1991: Torchwood Tower is built to cover up a crack in the multiverse.
1995: Torchwood Numbers 5-8 are shut down.
1999: Lucas North joins TW9. The legendary Torchwood SUV is created and sent out to all open branches. Retcon is created and perfected.
2000: Jack Harkness takes over Torchwood Cardiff.
2002: All ties between Torchwood 1 and Torchwood 3 are cut.
2003: Torchwood 4 disappears (the Hub and everyone in it). Torchwood starts to spread information amongst conspiracy circles the Torchwood House has burned down.
2004: The Birmingham, Liverpool, Hull, Newcastle-Upon-Tyne and Cornwall Hubs are decommissioned and the branches are merged with Torchwood One. An incident at Torchwood 10 results in the destruction of the base and the deaths of most of the staff. Only four survivors are reported. As part of restructuring, Torchwood 10 is re-numbered as Torchwood 5.
2005: Torchwood’s weaponry is used to shoot down a Sycorax spacecraft, revealing more than one Hub in London.
2006: Cybermen and Daleks fight all over London, destroying Torchwood Tower and killing all but 27 members of Torchwood One. This event is renamed ‘The Battle of Canary Wharf’. The branch is closed down by Queen Elizabeth II, along with the Torchwood Trust Committee. A Future Options Committee is set up.
2007: Torchwood One has been recreated as Torchwood Beta under the direction of Lucas North. The F.O.C. is merged into the newly revived Torchwood Trust Fund. The word Institute is dropped.
2008: Following an attempted Cyber invasion Torchwood Zero and Two were destroyed. Their Directors were suspended (reinstated later that year) and the Hubs rebuilt, as well as Torchwood House and Glasgow Tower.
2009: Torchwood’s name and reputation is known to the general public of U.K.
2012: Torchwood has become a lot more public, with the Battle of Canary Wharf being renamed the Battle of Torchwood.

Map Of Torchwood Hubs