Day 1: Kaleiçi Old Town
Spend the day exploring Kaleiçi on foot — Hadrian's Gate, the Clock Tower, Yivli Minaret and the old harbor. End the day with dinner at one of the marina-side restaurants below the city walls.
Day 2: Waterfalls and a Boat Tour
Visit Düden Waterfalls in the morning, then take an afternoon boat tour along the coast — a good combination of a short land excursion and a slower-paced activity for the rest of the day.
Day 3: Ancient Sites or Beach Time
Choose based on your interests: a half-day trip to Perge or Aspendos for Roman history, or a relaxed day at Konyaaltı or Lara beach if you'd rather spend your last day unwinding before departure.
This itinerary works well as a standalone city-break or as the first three days of a longer resort-focused trip — Kaleiçi and the nearby ruins are genuinely worth doing before you settle into resort mode.