St Andrews is the smallest town in the world to deserve a long visit. The four reasons are golf, ruins, university, and beach — between them they will fill two or three days, with everything within a 20-minute walk.
The cathedral and the castle are the essential historic sites, and the climb up St Rule's Tower gives the best view. Walk North Street and South Street to find the medieval and Georgian core of the university and the chapel of St Salvator's. The Old Course closes for play on Sundays, when the fairways can be walked freely; the British Golf Museum next to the R&A clubhouse covers the history for anyone who can't get a tee time. The West Sands and East Sands beaches frame the town, and the harbour at the foot of the cathedral cliff is small but pretty. After dark, the cobbled lanes between Market Street and the cathedral fill with students; St Andrews has a denser pub-per-head ratio than any town its size in Scotland.