On 18 May 2026, as part of the International Museum Day celebrations, Palácio Nacional da Ajuda will hold a special event entitled «Machines of Vision and Representation» focusing on two optical devices from its collection: a 19th century megalethoscope, and a rediscovered late 18th-century optical box.
The event builds on the photographic survey undertaken by the Early Visual Media Lab and ImHerit – Centre of Excellence (FilmEU) to document this 18th-century optical box, and to reconstruct it digitally. This work aimed to disclose this rare historical object and contribute to a broader public discussion about media heritage, fostering the conditions for its restoration.
This royal optical box will be presented for the first time to the general public. This is one of the rare surviving objects from the Portuguese Royal Cabinet of Physics, established in 1777. The Cabinet was initially planned for the education of Queen Maria I’s two sons, Dom José and Dom João (who would later reign as King João VI). This optical device is made of a wooden structure and two circular double-convex lenses, which intensify the sense of perspective and depth of the vues d’optique positioned inside. Palácio Nacional da Ajuda holds an extensive collection of such hand-coloured prints.
The megalethoscope is a mid-19th-century optical device designed to view large photographs with an illusion of depth and a three-dimensional effect. One of its most fascinating features is the ability to illuminate photographs in ways that create day-and-night effects.
The two apparatuses belong to a rich history of early immersive visual culture in Europe, in the crossroads between science, art, and entertainment. As part of the International Museum Day programme, visitors will have the opportunity to learn more about both objects, exploring their historical context, their place within the broader development of optical devices, and the ways they can still be relevant to our contemporary media landscape.
This free-admission event will begin at 4:00 PM, as a collaboration between Palácio Nacional da Ajuda, Instituto de História da Arte – NOVA FCSH, and Early Visual Media Lab – CICANT (Portugal).
