Apache, you just added Tomar to my list.
FWIW, here's my two cents about Portugal, which is one of the friendliest countries in Europe. The starting point is Lisbon. There's a rich history, which you should look up before you go. There's a great introductory museum on the Praa do Comrcio, by the Tagus River. I recommend starting there. Download the Rick Steve's app and his Lisbon walks.
Here are a few Lisbon highlights...
So Jorge Castle
Tower of Belem
Monument of Discoveries
Jernimos Monastery
Lisbon Tile Museum (overlooked and missed by most Americans)
Just outside of Lisbon is Sintra. It's a quick train ride. Here's the Castle of the Moors.
Pena Palace (stunning)
We didn't have time to visit both and had to choose between Porto and the Duoro Valley to the north versus the Algarve to the South. We went north, which was the wrong choice. We have a running debate in our house about the ugliest city in Europe. It's between Porto and Athens. Rick Steves describes Porto as "gritty." That's probably how he describes Detroit. The best thing about Porto is the Livraria Lello, which inspired JK Rowling's Diagon Alley. The Duoro Valley was beautiful.
Livraria Lello
Duoro Valley