San Niccolò is the quietest corner of the Oltrarno, a thin shelf of village between the river and the hill that climbs to Piazzale Michelangelo. It rewards a slow afternoon: the Arno on one side, low lanes on the other, and a medieval gate at the end that's never been cut down to size.
Under three kilometres, walked east from the centre. Start on Lungarno Torrigiani just past Ponte Vecchio, where the south bank hands you the whole skyline — bridge, towers, the Duomo dome beyond — with room to breathe. Turn inland onto Via di San Niccolò, the village spine, past wine bars and unmoved workshops, with the neighbourhood church and its Bicci di Lorenzo Madonna a short step off it.
The walk lands at Porta San Niccolò, the only city gate never shortened — the hill behind it made height an irrelevance — standing at full medieval reach above Piazza Giuseppe Poggi. Sit by the fountain grotto with the tower over you. Drift back along the leafy Lungarno Serristori if there's light, then take the C3 minibus from the gate.