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The largest play structure in the world

Lilidorei at Alnwick Garden at dusk showing play area and toadstool


Alnwick, United Kingdom


Duchess of Northumberland



Lilidorei, the world's largest play structure, is located near Alnwick Gardens. As the third major attraction added to the Gardens, it plays a key role in boosting tourism in the Northeast. The concept was created 12 years ago by The Duchess of Northumberland, offering an extraordinary experience for all visitors.

Embracing the historic landscape, we carefully considered the topography and developed a plan to allow the landscape to camouflage the structures into the surrounding area. We had to modify a long underground culvert while considering existing trees and root protection zones. As a team we overcame challenges, including over land flows, by developing and using overland flood modelling.

Carl Archer, Senior Civil Engineer, commented, “Lilidorei was a unique, challenging and rewarding project and it was great to see it being constructed after years of involvement. From civil engineering point of view, the project included public sewer diversions, culverting a watercourse, major earthworks analysis and challenging external levels design.”

Key fact

Lilidorei is the biggest play structure in the world.


Key fact

The project featured on the Channel 4 documentary “The Duchess and her Magical Kingdom”


Paul Hards in front of glass bamboo effect panelling

Paul Hards

Partner, Structural Engineering

View bio

This was a complex project with challenges due to the landscape, but we overcame these by adapting the structure to be more suited to the surroundings. It was exciting to work on a project with such a positive outcome for society, providing more local work and benefiting the school community by giving them a place to socialise.