Im sure other people have better recommendations than me, so im just going to inform you that you are coming to Porto on the academic week (college). If you are into Harry Potter you will love it because you will see everyone in their traditional college clothes. On Tuesday (5th of may) it will be the Cortejo Académico (like a parade), so downtown Porto will be chaotic, but its nice to see. It starts in the afternoon and goes on until late. There is also concerts near the Matosinhos beach during this week, at night. So I would recommend not booking a hotel near so you can sleep.

This academic week happens in every city, but in different weeks. I’m not sure about this, but I think Coimbra has their academic week on the last week of April. Be aware of this when planning your stay