The Nightmare Realm: Everything to know about London's new Halloween horror experience

As data shows Brits are preparing for Halloween earlier than ever in September, an exciting new horror attraction is preparing to open its doors in London for the first time.

The Nightmare Realm will take over the historic Grade II-listed Avery Hill Mansion in Greenwich for 18 nights from 9 October to 1 November, transforming the historic property and its grounds into a bone-chilling live horror experience.

This comes as data shows UK search interest in “Halloween event” during the first week of September surged 70% compared with the same period last year, while interest in “Halloween” itself was up 20%.

YouGov research also found 28% of Halloween planners begin preparing around a month ahead, while one in five Brits (21%) say they wish there were more Halloween activities available locally.

At The Nightmare Realm, visitors will enter an immersive Halloween world featuring two large-scale horror attractions, five secret experiences and Halloween Town, where live performers and roaming characters bring stories to life around them.

New images released ahead of the opening show some of The Nightmare Realm’s characters descending on Greenwich, carrying a coffin past the Cutty Sark in a sinister pre-dawn funeral procession.

The bloodied figures were pictured stalking through the area in gothic costumes and gruesome make-up, before “measuring up” unsuspecting Londoners to see whether they would fit inside the coffin.

What to Expect at Avery Hill Mansion

At the heart of the London event are two large-scale immersive horror attractions, Avery Hill Asylum and Sundown Manor, combining live performance, cinematic storytelling and elaborate sets.

Sundown Manor takes visitors into the home of an ancient vampire bloodline ruled by Lady Sundown, while Avery Hill Asylum introduces the sinister world of Dr Thorne.

Visitors will also enter Halloween Town, an immersive world populated by roaming characters and live performers, with five secret experiences hidden throughout the Realm, ranging from an exorcism to a Ouija board.

There is no fixed route through Halloween Town, allowing guests to explore at their own pace and discover characters, stories and unexpected encounters along the way. The entire experience takes around two hours.

A New Halloween Attraction for Greenwich

The Nightmare Realm first opened in Ireland in 2009 and has since welcomed visitors from more than 60 countries. Its arrival in Greenwich marks its first event outside Ireland, with a completely new experience created specifically for Avery Hill Mansion featuring original characters, environments and scares.

Karl O’Connor, Founder and CEO at The Nightmare Realm, said: “We’ve spent 16 years terrifying people in Ireland, and now we’re finally bringing the nightmare across the Irish Sea.

“We’ve created a completely new Nightmare Realm for London and we can’t wait to open the doors.

“We want visitors to feel like they’ve stepped into another world, with characters to meet, stories happening around them and things to discover if they’re brave enough to go looking.

“We’ve got plenty of surprises waiting inside, the only question is whether Londoners will be brave enough to find them.”

The Nightmare Realm runs for 18 nights from 9 October to 1 November 2026 at Avery Hill Mansion, Bexley Road, Greenwich, London, SE9 2PQ.

Tickets are sold for timed entry slots, with visitors advised to allow around two hours for the full experience. For tickets and more information about the event, visit The Nightmare Realm website.