Marginal

The Marginal — officially the EN6 coastal road — is the scenic route that runs along the northern bank of the Tejo estuary from Lisbon's Belém waterfront westward through the seaside towns of Oeiras, Estoril, and Cascais. For families, the associated riverside promenade offers one of the best free outings in the Lisbon area: flat, wide, and open with constant water views.

The experience works at whatever energy level the family brings. For active families, renting bikes in Cascais and cycling part of the route gives kids an adventure with natural endpoints and café stops along the way. For families with young children or strollers, a shorter walk along any section of the promenade — with the wind off the water and the view of ferries crossing the river — is a satisfying afternoon activity.

The Cascais end of the route is the most scenic and well-developed for tourism, with excellent seafood restaurants, a beach, and a charming town center. The Estoril section has the famous casino and garden. For families day-tripping from central Lisbon, the 40-minute train ride from Cais do Sodré to Cascais is easy and inexpensive, and the return walk or bike ride along the Marginal back toward the train can be as long or short as you want.