With kids, Plaza de Cibeles & Fountain works.
A 1782 marble fountain — Cybele riding her lion-drawn chariot — marooned on a roundabout and best admired from the edges, floodlit at night against the wedding-cake Palacio de Cibeles. Its real charge is football: this is where Real Madrid fans (and the players) climb the goddess to celebrate every major trophy, scarves knotted round her neck. Knowing that turns a photo stop into a place with a pulse.