Here at Londonist, we love exploring London's subterranean spaces — and we reckon you enjoy reading about them too. If you've done all the secret bunkers, ghost tube stations, tunnels and catacombs that London has to offer, how about having your next underground adventure in a cave? Here are some excellent specimens in and around the capital. By their very nature, they don't always make for the most accessible day trips, so do check ahead if you have specific accessibility requirements.
Chislehurst Caves, London Borough of Bromley
Jimi Hendrix played here (twice), Doctor Who was filmed here (you can still see the stage set glitter on some of the walls), and Led Zeppelin held a launch party here. Chislehurst Caves are certainly a site of cultural interest, if not of natural interest; all 22 miles of underground tunnels are manmade, used originally as chalk and flint mines.
Their exact age isn't clear. Rumours of Roman times are unlikely to be true, but they've come into their own in the last century. As well as hosting the mentioned pop culture events, they played a significant part in both world wars. During the first world war, ammunitions were stored here as an overflow site for Woolwich Arsenal, and in the second world war, 15,000 people sought refuge when the caves were used as bomb shelters. Read our full article here.
Chislehurst Caves, Caveside Close, Old Hill, Chislehurst, BR7 5NL.
How to visit: The caves are usually open Wednesday to Sunday (and everyday during school holidays). Access is only available as part of a tour. Tours run every half hour 10am-4pm and last around 45 minutes. £7 adults, £5 kids, book online or just turn up. Dress warm — even in summer, it's significantly colder in the caves than in the surrounding air.
Reigate Caves, Surrey
Similar to Chislehurst, a warren of caves runs underneath Reigate in Surrey — not that you'd know it, walking around the town at street level above. They're manmade 'caves', and split into two areas — Barons' Cave, and the Tunnel Road Caves.
The former gets its name from the entirely debunked myth that it's spot where barons met to draw up the Magna Carta in 1215. The original purpose of the cave is unknown, but it's thought to have been an important part of the Norman castle which sat above.
Back towards Reigate town centre, the Tunnel Road West caves were created as sandmines, while Tunnel Road East caves were dug specifically for storing beer and wine, both by local store Blackiston and Son, and by Reigate brewer Mellersh and Neale. During the first world war, both tunnels were used to store powerful explosives. Local families took shelter in Reigate Caves during the second world war, and they've since been used as storage, music rehearsal and performances spaces, and a shooting club, before being opened for public tours in 1991.
Reigate Caves, entrances on Tunnel Road and in the old castle grounds.
How to visit: The caves are only open to the public on certain open days (usually around five days a year —details here), although private tours are usually available for a minimum of eight people (private tours currently suspended).
Pope's Grotto, Twickenham
In the grounds of Radnor House School in Twickenham sits Pope's Grotto, a folly built by 18th century poet Alexander Pope when he lived in a villa on the site.
He decorated it with mosaics and colourful ores, stalactites and crystals. Sadly, Pope's habit for continually extending his grotto meant that he never saw it completed. It's now being restored by the Pope's Grotto Preservation Trust. We visited in 2018.
Pope's Grotto, Cross Deep, Twickenham, TW1 4QG.
How to visit: Access is restricted as Pope's Grotto is in the grounds of a school. You can normally visit on monthly open days, as well as during the Twickenham Festival in June and Open House London in September.
Scott's Grotto, Ware, Hertfordshire
The small town of Ware on the River Lea in Hertfordshire is a beauty, and if you ever have reason to visit, we suggest timing your trip to coincide with an open day at Scott's Grotto.
Like the best grottos, it's tucked nonchalantly down an otherwise normal — if hilly — residential road. Its entrance offers no clue to the 67ft of interconnected tunnels that extend into the hillside beyond. Shells, flints and pieces of coloured glass adorn the walls, and it was the handiwork of another 18th century poet, John Scott. His reason for building it is unclear — perhaps it was somewhere for him to write, or maybe it was an attraction designed to lure the learned and wealthy out of London to visit him. His visitor book contains more than 3,000 names.
After many years of neglect and a few near-demolitions, Scott's Grotto was restored, and has been open to the public since 1991.
Scott's Grotto, 34 Scotts Road, Ware, Hertfordshire, SG12 9JQ.
How to visit: Usually, Scott's Grotto is open every Saturday and bank holiday Monday between April-September. No booking is required, and there's a minimum entry donation of £2 per adult, which goes towards the grotto's upkeep.
Crystal Grotto, Painshill Park
Situated in the middle of the lake, the crystal grotto was created by Charles Hamilton, who built the whole park and its features as 'living paintings'. Stalactites hang from the ceiling, covered in crystals, bubbling water runs nearby, and it was used as a filming location for an episode of Black Mirror.
Painshill Park, Portsmouth Road, Cobham, Surrey, KT11 1JE.
How to visit: Access to the grotto is included in your ticket to Painshill Park (£11 adult/£5.50 child).
The Grotto, Leeds Castle, Kent
It's not the easiest grotto to get to, not just because of Leeds Castle's location in the Kent countryside, but because the grotto itself is buried in the centre of the castle's sizeable yew tree maze. Once you've found your way to the centre of the maze, exit via the underground grotto, purpose-built as an attraction with mythical beasts carved into the walls. Sure, it's a bit gimmicky, but it's worth a visit if you're at Leeds Castle.
Leeds Castle, Broomfield, Maidstone, ME17 1PL.
How to visit: Admission to the maze and grotto is included in admission to Leeds Castle — they cannot be booked separately. Tickets are £29-£32 adults, £21-£24 child.
Shell Grotto, Margate, Kent
We're ending on a mysterious note here, for the origins of the shell-studded cavern are unknown. A staggering 4.6 millions shells adorn the walls of the chalk grotto, which was discovered in about 1835, though various myths surrounding the date and circumstances of the discovery abound. The shells are predominantly mussels, whelks, oysters, cockles, limpets and razor shells from the British Isles, but the occasional exotic specimen, such as queen conches from the Caribbean, can be seen.
What you need to know is that it's stunning, it really is one of the most unique places you can visit on a day trip from London, and is open to the public. It's set a couple of storeys below ground level, on an otherwise normal residential Margate street. There's a cafe and small gift shop on site.
Shell Grotto, Grotto Hill, Margate, CT9 2BU.
How to visit: Shell Grotto is open daily in summer, 10am-5pm, with visits taking approximately 30 minutes. Booking required. Adult £4.50/ concession £4 / child £2.