Travelling to Porto

Hello Everyone, I hope everything is going on good!!

Me and some of my German friends will be travelling to Porto in end of May and would like to ask for some advice from you about sightseeing.

Which are the best beaches in and near Porto and which are the best clubs in Porto??

Also i am would like to do sightseeing in the city, so any advice about the Old city in Porto and its attractions??

Regards
nihit