Organised by the World Wide Fund for nature (WWF), Earth Hour 2017 will be staged between 8.30pm and 9.30pm this coming Saturday, 25 March.
The aim is for 150 Portuguese municipalities to sign up to the initiative after 120 took part last year. A total of 101 had signed up at the time of going to press.
As well as historic public buildings and monuments, the WWF aims for private citizens and households to also adhere to the programme by switching off their lights and taking part in activities organised to mark the date.
An official Earth Hour event is planned for Lisbon, at 8pm, which will be a candlelit charitable concert, featuring artists such as Raquel Tavares, Matias Damásio, Tiago Bettencourt, André Sardet, Tito Paris, Samuel Úria, Enoque and Janeiro.
Tickets cost €10 with revenue going to the WWF and its projects in Portugal.
Landmarks that will be switching off for the event include the 25 Abril Bridge (Lisbon), the Arrábida Bridge (Porto), the Rossio train station (Lisbon), S. Jorge Castle, the Jerónimos Monastery and the Belém Tower (Lisbon) and Loulé’s Castle walls (Algarve).
Earth Hour is a symbolic initiative that aims to raise awareness and invoke responsibility among people in the fight against climate change in favour of a sustainable environment.
In 2016, more than 7,000 cities in 178 countries and millions of people around the globe took part in Earth Hour.