While I was in Porto I was followed several times by various strange men. They ranged from curious locals to men seeking a love interest to downright shady characters. I only really felt in imminent danger once. Even holding up my hand and saying stop and yelling Policia did not always deter them. I was traveling alone and I think it would have helped to have a male companion to act as a deterrent, but if you are female and traveling solo, then I recommend a few things. Get in a crowd if you notice someone is following you, do an about face and walk in the opposite direction to see if they continue, look at them and say No and Policia, or if need be hop a public bus or other form of transportation to get away from them (they are not likely to want to pay to follow you around). Overall I want to say it was pretty safe there, just use common sense and be aware of those around you and have a safe and enjoyable time!
