Parc de la Ciutadella — the Cascada at opening time

The Cascada was built for the 1888 World's Fair, with a young Gaudí helping on the waterworks: a double stone staircase, a triumphal arch, grottoes, griffins and Aurora's gilded chariot on top. A small boating lake sits right in front of it, and palms and plane trees close the sides.

It is the one set in Barcelona that gives scale for free. Put two people on the lower steps and the arch rises behind them; move back to the lake and the whole structure doubles in the water; step in close and there are dragons, crabs and carved stone for detail frames. The ground is flat and pram-friendly, which is why family sessions end up here rather than on the Park Güell stairs.

Come in the first hour after the gates open. The park is quiet, the lake is unruffled and the stone is still in soft light; from mid-morning the plaza fills with tour groups, skaters and drum circles. In high summer the midday sun bleaches the pale stone and burns out the gilding — use the plane-tree shade instead, and in November those same trees drop a copper floor.

Five minutes away, the Arc de Triomf and its avenue of palms give a second, completely different set: red brick, symmetry and a long lead-in line. Both are free and open daily.