Belém here I am, the area stands out to be home for most of the historical glorious past of Portugal. You can reach this place using the Lisboa card and get discounted and free entries to most of the sites.
We took Tram No 15 to reach this place, which is longer route and takes more time, but we took it to see the city more while travelling the Tram. However, it was crowded and no place to even stand, let alone see the city. So my suggestion would be to take the Train and get off at Belém station and walk from there. And take the Tram or buses (714, 727, 728, 729, 751) in the evening while returning back to your hotel.
Torre de Belém (World Heritage Site)
Its best to start your sightseeing from the Torre de Belém (Belém Tower), as later on there will be a long queue to enter; due to limited number of people entry into the monument and the last admission is till 5 pm also a free admission with Lisboa Card.
Designed by Francisco da Arruda and in existence in Lisbon since 1521. A defensive complex at the mouth of the Tagus and greets the arriving ships of the Portuguese sailors.
Originally, a lighthouse on a rock in the estuary of the Tejo, there was a second tower on the opposite side. Enemy ships could be so caught in the crossfire. However, this twin tower was destroyed by the great 1755 earthquake. So within the Torre de Belém you will find spots for cannons that could shoot at enemy ships sailing towards Lisbon.
In 1983, the Torre de Belém was declared a World Heritage Site by UNESCO.
Some pics of the place and in one of them I am at a lookout for the Portuguese Ships or the enemies!… Oh! Where are they?