Legen - wait for it - dary !
We went to Lisbon in the worst time of the year weather wise (end of February) and still it blew our minds. The beautiful city had so much to offer that the five days just flew by too fast and there was so much more that we still wanted to see.
Insider Tip:Eat pastel de natas, drive around the city with the tram number 28 and get lost in the small neighborhoods up the hills. Also remember to drink a lot of cheap but oh so tasty portuguese wines while you're there and eat a lot of seafood!