Many people don't think to rent a bike to see the city, but I think it's one of the best things you can do since Thessaloniki is right on the water and you will get some amazing views. Unlike different cities nearby, like Kavala, Thessaloniki doesn't have that many hills and is very easy to get around on the bike. I just recommend that you're careful of drivers, as Greek drivers can be a bit aggressive on the road. When I last visited, it was a few years back so I don't remember which bike rental company we used. So if anyone recommendations please drop them below.