Lisbon stay

Just for Lisbon, I would recommend a minimum of three full days.

Rick Steves guidebook has some waling tours. Be sure and do the one from St. Georges Castle. Also, you will want to go to Belem to the monastery and monuments on the river. Also, have one of the wonderful pateles or pastries.

Also, consider day trips to Evora, Sintra and Obidos/Batila Cathedral. Plan on going to a Fado show.

Hard to answer your question without knowing your interests. Most travelers come home wishing they would have had more time in Lisbon. I have been there many times and have yet to lose interest. Depending on your intertests, a week in Lisbon (with several day trips out of town) would not be too much for most travelers.

Hello becky.sahlfeld,

It's great you're coming to Portugal :)
There is a lot to see in Lisbon and it all depends on your interests: there are some must-see monuments like the Jerónimos Monastery, Belém Tower and São Jorge Castle; exploring the historic quarters like Alfama; visiting some museums (there are many to choose from)...
Apart from visiting Lisbon, you'd need at least one full day (I recommend two days) to day trip to Sintra (wonderful cultural landscape)... There are other day trips to consider but this is the one I'd choose ;)
All in all, I think you'll need at least 5 days to begin with but, as I said before, it'll depend on your tastes (and the number of day trips you to do ;) ).

Enjoy Portugal ;)

I would say that 3 full days is the absolute minimum stay but I agree with Paulo that 5 days would be better as it would allow for some wonderful day trips - Sintra and Evora both easily done and very worthwhile. You’ve already invested in airfare to get to Lisbon from North America, so weigh the cost of the hotel room for an extra two nights against just skimming the surface of a beautiful area of Europe. If you have the time, linger longer.