10th June is a very important date in the Portuguese calendar, it marks Portugal's National Day.
The date is chosen to commemorate the anniversary of the death of poet Luís de Camões in 1580. Camões is revered as the greatest Portuguese-language poet, compared to the likes of literary greats such as Shakespeare and Homer. His greatest work is 'The Lusiads' which celebrates Portuguese achievements, particularly the country's roles in the Discoveries during the 16th century, it was this work that made him popular amongst his countrymen, and he was particularly lauded during Salazar's authoritarian rule. A statue of Camões can be found in Lisbon.
Portugal Day is a national holiday and people generally celebrate with parades and parties.