Notes

If you like to walk, you should go to the 7 hills of Lisbon that are actually 8, but here's a little bit about it: https://www.flytap.com/en-us/destinations/suggestions/the-seven-hills-of-lisbon  and this link talk a little bit more about it: http://www.ancient-origins.net/ancient-places-europe/seven-hills-symbol-magic-lisbon-003317

At night you can go out in Santos, there's some clubs there or if you prefer some bars you can also go to Bairro Alto (which means tall neighborhood, because of the hills I guess)

Now I don't know if you guys wanna spend money on things like the Zoo and Oceanarium but I always love to see that
Here's the links, zoo: https://www.zoo.pt/site/index_en.php
And oceanarium: https://www.oceanario.pt/en
They're both pretty big and beautiful !
But I understand if you guys wanna visit other places and if so, the location of the oceanarium (parque das nações or Nations Park) is pretty nice to walk around with the river by your side, you also have a big shopping center and a cable car over the river


But better than this maybe is Belém. You gotta go there! You have a lot of historical places as well as parks and a beautiful view of the river
You also have the amazing Pastéis de Belém (which is an amazing typical Portuguese Pastery that you need to taste)
You can find all about this things here: http://lisbon-portugal-guide.com/belem-lisbon/belem-lisbon-walking-tour-1.html

From Lisbon you can catch the train to Cascais, beautiful city as well, here's some of the places you can visit there:
http://www.cascais-portugal.com/Guides/Cascais-Walking-Tour.html

And to finish in greatness you definitely HAVE TO visit Sintra!! It's a beautiful nature escape, you have a lot of monuments, it's a pretty old village and it's on the hills. It's really amazing because it has this special microclimate that adds everything to this mystical village. It has a handsome castle, a wonderful palace and an unique extraordinary house called Quinta da Regaleira that was constructed in 1898 (if I'm not mistaken) by a crazy/really reach guy and it even has secret passages and everything! Sintra is this magical and mysterious town that you can't cross off your list! It has awesome and beautiful trails to hike through the Nature to the colorful Palace on the hills but if you don't feel like hiking you can take the bus and watch the Landscape.
Here's the link to Quinta da Regaleira: http://www.regaleira.pt/Default.aspx
Here's a guide about Sintra: http://www.sintra-portugal.com/index.html

Now, while you're there, you must go to Piriquita that it's a typical pastery in Sintra. It's also pretty old, it has about 160 years since the times of our Kings and Queens and it makes awesome and really tasty amazing typical pastries from Sintra (Queijada de Sintra and Travesseiros). Grab this with an expresso and you're good to go! :)   here's the link: https://www.piriquita.pt/?lang=en