Since then admission has been free on the first Sunday of the month, all day, rather than every Sunday for part of the day.

The decision to restore free admission on Sundays to 2pm was announced earlier this month in parliament by the minister of culture, Luís Filipe Castro Mendes.

To mark the charge this Sunday, the minister is to visit the Museu Nacional Machado de Castro, in Coimbra, where a book on 100 years of that museum is also to be launched.

Speaking in parliament, the minister described the measure as "emblematic for Portuguese to get to know the museums more and better".