Have You Heard Of The Clerkenwell ‘Catacombs’?

Unbeknownst to many, hidden beneath Clerkenwell, is an eerie historic survivor: the Clerkenwell ‘catacombs’. They are the only surviving fragment of a much larger Victorian prison complex that once dominated this area of the city.

They are rarely open to the public, however there is an opportunity coming up very soon to see them, more on that below.

origins

Clerkenwell Prison, or the Middlesex House of Detention, has its origins back in 1615. A prison was built on the site, at the Northern edge of the city and seems to have been originally split into two parts: the ‘New Prison’ for those actually convicted of crimes and the ‘Bridewell’ for those who were awaiting trial at the nearby Middlesex Sessions House.

Middlesex Sessions House, originally called ‘Hick’s Hall’, was demolished and rebuilt in 1782. You can still find that building on Clerkenwell Green, now a hospitality and events venue called Old Sessions House, after a large restoration project. 

The Prison Rebuilt

The prison was rebuilt in 1847 and called the Clerkenwell House of Detention. It was a three-storey structure, designed by William Moseley based on the radial model of Pentonville Prison. This meant that it featured a central hall with radiating wings for maximum visibility. The prison operated a ‘separate system’, meaning that where prisoners had previously been kept in overcrowded communal cells, now they were in individual cells.

It was eventually demolished in 1890. That is, all except the ‘catacombs’.

The ‘catacombs’, a modern nickname by the way, partially constitute some of the 286 prison cells that made up the prison. According to Historic England, this was once part of the female corridor. There are other spaces that were once the warder’s hall, the clerk’s office and other service spaces.

At 9,000 square feet, they are pretty expansive, with lots of intriguing nooks and crannies, where the imagination can run wild. 

Today they can be found beneath what was initially Hugh Myddelton school, opened 1893. The school closed in 1973 and the building is now flats. 

During World War Two the vaults were also said to have been used as an air raid shelter. Many spaces like this were utilised in the Blitz to give some sort of cover during air raids. 

Jack Sheppard Escape

One of the notable prisoners at Clerkenwell was Jack Sheppard. Jack Sheppard was an infamous 18th century criminal, who became a folk hero in the city for his numerous daring escapes from prison. 

Sheppard was locked up in Clerkenwell in May 1724 after being arrested for pick-pocketing in Leicester Fields, with his mistress Elizabeth Lyon. They escaped after just a few days by, it is said, filing through their manacles, removing a bar from the window and lowering themselves down with their knotted bedclothes. They then somehow managed to climb over the nearly 7 metre high exterior wall of the Bridewell into the streets. 

This was his second escape, having previously escaped from the St Giles Roundhouse. He would be arrested twice more and escape twice more from Newgate prison, once disguised in women’s clothing and the second by climbing up a fireplace and breaking through various doors. 

Jack was arrested for the fifth and final time on 1st November 1724. He was sent to Newgate, had 300 pound weights attached to him and watched at all times. He was eventually hanged at Tyburn on 16th November in front of a crowd of tens of thousands. 

An Explosion That Rocked The City

At 3.45pm on the 13th December 1867 a loud explosion was heard and felt across the city. 

It was the work of a group of members of the Irish Republican Brotherhood, known as ‘Fenians’, who were trying to end British rule in Ireland. They had placed a huge barrel of gunpowder against the wall of the prison exercise yard in Clerkenwell and detonated it with a firework.

The idea was to aid the escape of fellow Fenians Richard O’Sullivan-Burke and Joseph Casey, who had been recently arrested. The plot however was an unmitigated disaster. The authorities had been tipped off and the prisoners already been moved to another location. The group also had unfortunately used far too much gunpowder. Many windows within half a mile radius were blown out and a 60 foot stretch of the prison wall was destroyed, along with many tenement houses on the other side of the street. Over 100 were injured and 12 were killed, including children.

It became known as the ‘Clerkenwell Outrage’ and sparked a massive anti-Irish nationalist backlash. The Times newspaper described it as a ‘crime of unexampled atrocity’.

The most significant action of the Fenians in Britain, this event helped to fuel hostility toward Irish nationalism for decades. Arrests were made and a man called Michael Barrett was sentenced to death for being a part of it, something he always denied. Barrett was hanged publicly outside Newgate Prison on the 26th May 1868, the last public execution to take place in Britain. 

The ‘Catacombs’ Today And How You Can Visit 

The ‘catacombs’ are, unsurprisingly, used as a filming location regularly today. They have appeared in Sherlock Holmes, the Dark Knight, Silent Witness, Spooks, Luther and Horrible Histories. 

Clerkenwell Design Week have also used the space regularly during their festival. The festival has been going on since 2009, celebrating Clerkenwell as a hub of architects and designers. 

This year (2026), it is on from the 19th-21st May and they are using the catacombs for their lighting designs showcase. You can find out more about specifically here.

You must register (for free) to visit, which you can do here on their main page. It is taking place across various historic and interesting venues in the Clerkenwell area. 

Thank you for reading, more of London’s hidden historic locations below…