Heritage and historic monument lighting

Lighting a monument is not the same as making it visible. The studio designs light for churches, medieval walls, palaces and World Heritage sites across Portugal, and Diana Delnegro was responsible for the lighting of Lisbon's monuments for more than fifteen years, from Praça do Comércio to the Marquês de Pombal: light that adds to a building's worth at night, and protects it.

Conserving a landmark's image does not mean returning it to its original state, which for most historic buildings was the darkness that preceded electricity. It means respecting what the building symbolises and what its builders intended, and adding value without distortion. Artificial light governs perception in a way daylight cannot: it can reveal what goes unnoticed by day, the coursing of the stone or the marks of the masons, and it can as easily make a building unrecognisable.

The method comes from conservation as much as from lighting. Every intervention is reversible and discreet, so that what is lit is protected: fittings kept off the historic fabric wherever the architecture allows, light directed with precision so that nothing spills into windows, onto the sky or across the street, and the quantity of light set by the surroundings, so that a monument does not have to compete with the street lighting around it. Colour temperature and colour rendering are chosen for the material, granite, limestone, tile or gilded wood, and the installation can dim through the night on a schedule.

At the Fernandine Walls of Porto, medieval walls hidden by new building and drowned by intrusive street lighting were returned to the night landscape with grazing light that reveals the stereotomy of the stone, an intervention that is entirely reversible and that earned an Honourable Mention at the LIT Awards 2025. In Lisbon the studio lit the Igreja da Conceição Velha, the Igreja da Graça and its belvedere, the Santa Casa da Misericórdia and the Igreja de São Roque, the Igreja de São Jerónimo, the Monument to the Dead of the Great War and the columns of Parque Eduardo VII. In Tomar the lighting of the cloisters of the Convento de Cristo, a UNESCO World Heritage site, is in development, and in Porto Alegre, Brazil, the studio designed with three other lighting designers the lighting of 55 cultural landmarks of the historic centre as a single plan.

Diana Delnegro holds a master's in the Rehabilitation and Conservation of the Built Heritage from the Instituto Superior Técnico and is the author of Arquitectura em luz: a iluminação exterior do património, published in 2012, a study of exterior lighting as the instrument that controls how heritage architecture is read. She chairs CIE Technical Committee 4-59, which is developing the international Guide for Lighting Urban Elements: how monuments, facades, bridges and sculptures should be lit.