Routes:

AIRPORT  (11 km /6 miles from/to the city center)  www.ana.pt

If you come by plane, the best way for reaching the city center is the subway.

(purple line E - direction: Estádio do Dragão)

It works from 06:00 until 01:00

You must by a Blue Card "Andante" (0€50) and charge-it with a Zone 4 (1€80) = 2€30
You must keep-it because it's rechargeable according to the zones in the metropolitan area in which you travel in any public transport (metro, bus, tramway or train).
(with a Zone 2 (1€20) you can circulate almost everywhere in the city).

Nb: Andante must always be validated when you start a trip, 
on changes of line and changes of transport (lasting up to one hour)