you can't go to rimini without checking La Baia Imperiale (i think it's in Cattolica, close to Rimini)
roman style + an impressive amount of cockchildren!
that's the highest art expression you will find in Rimini, sry for that

oh, a little advice:
Rimini is full of "vuccumprà". In order to dodge them, you just need to wear a hat/cap. Yeah, a cap. I'm not kidding.
Hats and caps are the best items that a vuccumprà can offer to his customers, so if you have one already, the vuccumprà will be very confused and won't be able even to start a conversation

enjoy the sea!
an other advice
if some italian guys come close to you, walking in a strange way, with big sun glasses and they say "WEEE HEY RAGAZZI ALLORA STASERA TUTTI ALLA BAIA???" you must punch them on their noses with no mercy. Trust me, it's for their own sake
