Cafes, restaurant terraces, museums, and gyms have been reopened with Portugal to limited capacity, but strict travel restrictions remain in place.
Portugal has begun easing its COVID-19 restrictions as part of the country's second phase of a gradual decontamination plan.
500,000 schoolchildren up to the age of 15 returned to classes on Monday for the first time since Portugal went into lockdown in January. Primary school students had already returned for lessons on 15 March.
Cafe and restaurant terraces were also reopened on Monday with a maximum of four people allowed to sit together.
Meanwhile, museums, national monuments, small streetside stores, and gyms opened their doors again as well to a limited capacity and strict sanitary rules.
However, some museums have stated they do not expect many visitors as many foreign tourists are still prohibited from entering the country.
Flights to and from Brazil and the UK remain suspended to limit the spread of new variants of the coronavirus, while some land border controls between Portugal and Spain have been extended until mid-April.
After a sudden increase in cases in January, Portugal became the worst-hit country in the world by size of population, prompting the government to impose a second national lockdown.
But mainland Portugal's 14-day incidence rate of COVID-19 cases per 100,000 people has now fallen to 63, after being recorded as high as 1,628 at the end of January.
The government's decision to return secondary school pupils to classes on Monday is based on mass screening and a vaccination plan for teachers.
If the situation continues to improve, high schools, universities, and theatres will reopen on April 19, under the deconfinement plan.
Since the start of the pandemic, Portugal has recorded 823,355 cases and 16,879 deaths from COVID-19.