Not to miss

Student Detention Rooms

Jokes, duels and drinking could land yesterday's uni students in the clanger (Studentenkarzer). Being put away for such Kavaliersdelikte (minor offences) was the done thing for young 19th-century gentleman-scholars. Visit to see how today's graffiti measures up against the industrious doodling of detainees - here for anything from three days to four weeks.

Heidelberg Castle

Partly ruined, the castle (Schloss) still gets gasps. Even Mark Twain marvelled at its 'dainty and elaborate' decoration. Gulp at the castles promisingly huge keg: Grosses Fass can hold 220,000l (464,000pt). Also worth a visit is the castle's Pharmacy Museum. Unfortunately, the less-than-scintillating interior can only be seen by guided tour - an extra charge.

University Library

Architecturally, this library (Universitätsbibliothek) is a mongrel - but one of those rare, good-looking crossbreeds. The Art-Nouveau elements make sense - it was built at the turn of the century - as do, weirdly, the 16th-century Deutschmanierismus motifs. Upstairs, you'll see rare books and prints from the library's superb collections.