Madrid is an easy city with children — late hours mean nobody glares at a 10pm toddler, plazas are traffic-free playgrounds, and the heavyweight sights all have a kid-sized angle if you play them right. The region adds the outdoor layer: a walk-on castle, river pools, and a train that climbs a mountain.
Everything below is ordered city-first, region-second, with the heat-wave alternatives marked — August afternoons need a plan B.
€6 of guaranteed success on the Estanque, then the puppet theatre (weekends) and the Crystal Palace's fish pond.
The 2.5 km cable car from Parque del Oeste over the river to Casa de Campo — picnic, playgrounds and the lake at the far end.
The Natural Sciences Museum's dinosaur hall is world class and never crowded; combine with the giant-squid corner and the park outside.
Do the Armoury (knights, tiny children's armour, horse mannequins) and the throne room, then quit while ahead — the gardens absorb the rest of the visit.
Battlements to patrol in the morning, the Pedriza's icy river pools after lunch — 50 minutes from the city, the best family day in the region.
A real narrow-gauge train to 1,800 m — snow play in winter, easy lagoon walks from Cotos in summer. The ride itself is the attraction.
Costumed hostesses hand out strawberries on the 1851-route heritage train to Aranjuez — spring and autumn weekends, book ahead.
The gentle dammed pools below El Paular monastery, with meadows for the picnic blanket — the family end of mountain swimming.