Puerta de Alcalá
The restoration of the Puerta de Alcalá – a symbol of Madrid and part of a UNESCO World Heritage Site – combined traditional craftsmanship and scientific analysis in a large-scale public project, setting new standards for transparency, research, and public engagement.
The Puerta de Alcalá, one of Madrid’s most iconic monuments, has undergone its most ambitious restoration to date. Erected between 1769 and 1779 by architect Francesco Sabatini for King Charles III, the triumphal arch is a defining landmark in the heart of the Spanish capital. Today, it forms part of the “Paseo del Prado and Buen Retiro, Landscape of Arts and Sciences”, inscribed on the UNESCO World Heritage List in 2021.
In 2022, the Madrid City Council launched a comprehensive restoration based on international heritage standards. Fully funded by the municipality, the project followed a dual methodology that combined historical research and scientific diagnostics with traditional craftsmanship. More than 100 specialists, including conservators, engineers, blacksmiths, stonemasons and sculptors, collaborated to analyse and restore the monument. Using 3D laser scanning, structural modelling, ultrasonic testing and laboratory material analysis, the team identified vulnerabilities in the stonework and internal metal frameworks. These studies confirmed the original artisans’ technical sophistication and guided every intervention.
Hands-on restoration work was carried out with great precision. Granite and limestone surfaces were cleaned, stabilised and consolidated. Sculptural elements were secured with new wrought iron or brass fixings where needed, while stable historical fittings were retained. Missing details were recarved in natural stone from original quarries using traditional tools. Lime mortar grouting and manual carving techniques were employed throughout, closely following 18th-century construction methods. Where possible, original elements were preserved; replacements were introduced only when strictly necessary and were carefully matched to existing materials.
The restoration project of the Puerta de Alcalá included extensive outreach. A website documented the works, and over 12,000 people participated in “Open for Restoration” tours, climbing scaffolding to view the monument at close range. A dedicated campaign – entitled “Conserving the Landscape. Enjoying the Light” – framed the project as part of Madrid’s commitment to safeguarding its World Heritage Sites. A technical conference was also held to share results and methodologies.
To protect the restored monument, a preventive conservation system was introduced. Environmental sensors now monitor vibration, humidity and structural behaviour. In an ecological measure, trained birds of prey were used to deter pigeons, avoiding the use of invasive anti-roosting devices.
This large-scale public restoration also resulted in the first complete digital record of the Puerta de Alcalá’s interior and structure. Together with the extensive documentation and outreach tools, this provides a long-term resource for conservation and research, and serves as a reference for similar projects across Europe.
“The restoration of the Puerta de Alcalá, a key urban landmark in Madrid, exemplified the integration of modern scientific methods with traditional craftsmanship,” the Awards’ Jury commented. “Extensive public engagement accompanied the works, including guided scaffold tours, multimedia outreach, and on-site interpretation,” the Jury remarked.
Contact: Blanca Mora Calderón, Head of the Restoration and Historical Heritage Service | Department of Culture, Tourism and Sport of Madrid City Council | moracb@madrid.es | www.restauracionpuertadealcala.es