the great museums of the city. Now we want to visit Frankfurt,  the city of art, and specifically go to the museums. Staedel, Schirn and Museum of Modern Art are on offer.  So if we drink a cappuccino in the old town and want a snack, a single day is already too short. Frankfurt is worth more than one visit only - you should come two or three times.
Summer weather without much heat would be ideal.