Mainz, Germany is one of the many industrial cities of the Rhine River area of that country.
My friend and I went to Mainz to take a Rhine River cruise. Unfortunately on September 10, we had missed the boat by 10 minutes and decided to cut our losses and make a day of it visiting the sights of Mainz.
My friend and I went to see the Mainz Cathedral. It is a Romanesque Cathedral built during medieval times and is the main attraction of Mainz. The interior is large and cold and has many statues of saints and priests who preached in the Cathedral. The exterior is dirty and grimy from industrial dust and grime that spews on Mainz from the factories in the area.
It was raining that day in Mainz, so my friend and I went walking with umbrellas around Mainz's main square, where there are many shops to see and shop in.
There is not much to see once you leave Mainz's center, but you could go to Rudesheim and other cities nearby. Mainz is a good day trip from Frankfurt and easily reachable by train, bus, or car.