Day 1 — Old Town & the river
Start in the Old Town Square, ideally before 9am, to see the Astronomical Clock and the square itself without the crush. From there, wander the lanes toward Charles Bridge and cross it slowly — this is the walk people actually picture when they think of Prague. In the afternoon, loop back through the Jewish Quarter, then find a beer hall for dinner (see our food & drink guide).
Day 2 — The castle side
Cross the river and spend the morning at Prague Castle, which needs a real half-day if you want to see the cathedral and courtyards properly rather than rush them. Work your way downhill through Malá Strana in the afternoon, and if you've got energy left, climb (or take the funicular up) Petřín Hill for the best sunset view over the rooftops.
Day 3 — Vyšehrad, or further afield
Two good options for day three. If you want a quieter, greener side of Prague with fewer visitors, spend the morning at Vyšehrad and the afternoon exploring the New Town around Wenceslas Square. If you'd rather leave the city entirely, this is the day to take a day trip to Český Krumlov or Kutná Hora instead.
If you only have 2 days
Merge days one and two: Old Town and Charles Bridge in the morning, the castle in the afternoon (accept that you'll be moving faster through it), and save Malá Strana and Petřín for whichever daylight you have left. Vyšehrad and day trips are the first things to cut.
What to book ahead
You can turn up and walk most of this itinerary. The exceptions are Prague Castle's paid interiors (St Vitus Cathedral, the Old Royal Palace) in peak season, and any specific restaurant or tour you have your heart set on — both get busy enough in summer that a same-day booking isn't guaranteed.