Elizabeth Tower – Big Ben
The Elizabeth Tower, commonly known as Big Ben, stands at the north end of the Palace of Westminster and has told London the time since 1859. Designed by Sir Charles Barry with A.W.N. Pugin after the original Palace was destroyed by fire in 1834, it is one of the most enduring symbols of London and part of the Palace of Westminster and Westminster Abbey, a UNESCO World Heritage Site.
Previous interventions had taken place approximately every 25-30 years, in a periodic and constant maintenance and conservation programme. The intervention conducted between 2017 and 2022 is the most extensive in its 160-years history.This project aimed to safeguard the tower for future generations Surveys revealed water damage, corrosion of the cast iron roof, deterioration of the stonework and problems affecting the clock mechanism itself.
A specially designed 100-metre scaffold, which was braced but not attached to the Tower, allowed full access for repairs. Around 800 areas of damaged stone were repaired or replaced using Cadeby limestone that closely matched the original 19th-century Anston stone. Decorative carvings were recreated by stonemasons using traditional techniques.
The cast-iron roof, consisting of close to 3500 individual components, was dismantled piece by piece, repaired off-site and reinstalled, with more than 75 percent of the original material preserved. Clock dials were stripped, corrosion defects drilled out and repaired, and re-glazed with mouth-blown pot opal glass. Paint research revealed the original colour scheme, leading to the reinstatement of the Tower’s deep Prussian blue background and gold decoration. During the works, one clock dial continued to display the time using an electric motor.
Inside the Tower, earlier repairs that had trapped moisture were replaced with lime-based finishes that allow the masonry to breathe. Improved ventilation and conservation heating now regulate humidity. The clock mechanism was dismantled, cleaned and the automatic winding system was rebuilt.
General accessibility, as well as access for maintenance and emergencies, were improved through the installation of a lift within a former ventilation shaft, carefully threaded through the structure and enclosed in a new glass element in the belfry. Lighting was upgraded to LED, and mechanical and electrical systems were replaced. Maintenance access was improved, including new inspection points.
The project introduced Building Information Modelling (BIM Level 2), a digital system that records every stone and intervention in a three-dimensional model. This detailed digital record supports future maintenance and informs conservation work across the wider parliamentary estate.
Specialist craftspeople from across the United Kingdom contributed to the project, including stonemasons, glaziers, gilders and clock specialists.
The Awards’ Jury highlighted: “The prestigious conservation project of the Elizabeth Tower demonstrates an exemplary tradition of cyclical maintenance. It reinforces the monument’s symbolic significance while combining specialist craftsmanship, innovative materials and technologies, and rigorous documentation.”
Contact: Lorcan O’Donoghue | House of Commons | commonspressoffice@parliament.uk | www.parliament.uk