frankfurt a day at a time

[leefree]

in march, i'm going to be in frankfurt for a couple days, but at seperate times. the reason is because i'm mainly going to italy, but i foudn a great deal by flying round-trip to frankfurt then using ryan air to travel to/from italy. so anyways, i have about a day at the beginning of the trip and a day at the end of the trip and i'm looking for advice on what to do. i'm not too interested in club/bar hopping.