Parc Natural de la Serra de Collserola (Carretera de les Aigües)

Collserola – Sant Medir & Hermita Loops - Mountain trails on Barcelona's edge. 5-10km routes with elevation gain. Dogs love it but bring water - no fountains on trails. Parking at the Plaça de la Font del Racó fills early weekends. Best fall through spring - too hot in summer. Some areas allow off-leash but use discretion. Watch for mountain bikers. Stunning city views at the top.