Hello olissipom, yes I did forget Lisbon what a fool I am.
Were do you start! Belem this is tram 15 not as I put in the above I should have put tram 28 for the best views of Lisbon, right Belem as you put the Mosteiro dos Jeronimos is a must also at the other end of this building is the (Maritime Museum very good) the Torre de Belem from 1515 this is a Manueline gem and well worth a visit, the Monument to the Discoveries headed by Henry the Navigator with great views of the bridge and the statue of Cristo Rei, or perhaps the Museum of the Coches with all the Kings of Portugals state coches on the way by stop and have a Pasteis de Belem in the Antiga Confeitaria de Belem.
Lisbon as you again put the Castle you can get tram 28 part of the way up or go there by bus right to the gate or you can walk up and stop of at a few sites on the way the first is the church of Santo Antonio then round the bend to the Se (12th century Cathedral) a bit further up the hil is the church of Santa Luzia something to do with the Knights of Malta, at the side is two tiled panels one of pre earthquake Lisbon and one of cristians attaking the castle, also look out for the views of the city and river.
you can then follow the road round to the church of Soa Vincente de Fora or go up the hill to castle, there is a good cafe for a drink and to get your breath back before you go in ( you have to pay to go in now) but well worth it for the views. On the way back down try and find the way to the Military Museum I think one of the best sites in the hole of Lisbon.
In the Baixa area you could have a look round the Praca do Comercio with its big archway and statue of King Jose 1 and were the last king of portugal Carlos 1 was killed, then there is the Elevador de Santa Justa a Elevator with a cafe at the top again with great views and you can get travel cards the busses/trams and underground from here.
At the side of Rossio Station is the Elevador da Gloria up a big hill to Bairro Alto with the church of Sao Roque one of the most opulent in Portugal and Museum and the ruined church Igreja do Carmo left as it was after the 1755 earthquake.
If you fancy a half day by the seaside get the train to Cascais nice beaches and some good shops ( train for here is at the Cais do Sodre station )
The only other site you may have time to see is the Calousta Gulbenkian Museum its a bit out of the city but well worth a visit ( tube from the Rossio to Sao Sebastiao )
I think this will do for a two day visit hope this helps
Dave