Three days is the sweet spot for Sintra and Cascais. It lets you give the palaces the time they deserve, add the quieter forest sights that most day-trippers miss and still spend a full day by the sea. The plan below assumes you are staying one or two nights in Sintra and then moving to the coast, and it keeps the early starts for the day that needs them.
Before you go
Book your Pena Palace slot first, because the palace is sold by date and time and everything else is easier to move around it. Add Quinta da Regaleira if you are visiting in busy months, and keep the rest flexible. Pack comfortable shoes with grip, a light waterproof layer and a small bag, since the hills are cooler and damper than Lisbon and the lanes are cobbled.
Day one: the royal hill
Take an early train or taxi to Sintra and head up to Pena for your morning slot. The walk from the gate is steep, so use the shuttle if you prefer, and allow two to three hours for the palace, the terraces and part of the park. Continue to the Moorish Castle, which shares the same bus route and rewards you with ridge-top walls and long views. Come down to the village for a late lunch, then spend the late afternoon at Quinta da Regaleira, when the tour groups have thinned out and the Initiatic Well and tunnels feel mysterious rather than crowded. Finish with a pastry and a slow walk through the old centre, and have dinner in the village once the day-trippers have gone.
Day two: gardens, forest and the edge of Europe
Start with the quieter side of the hills. Monserrate Palace and its botanical gardens make a gentle morning, and the Convent of the Capuchos, a short drive away, is the perfect contrast: tiny cork-lined cells built into the rocks, with no decoration at all. A taxi or tour makes this part easy, because these sights sit outside the main bus loop. After lunch, continue west to Cabo da Roca, the westernmost point of mainland Europe, where the wind, the cliffs and the lighthouse make a memorable stop. If the weather is clear, stay for the late light, then follow the coast road toward Guincho Beach for a sunset walk on the dunes before heading to Cascais for the night.
Day three: Cascais and the coast
Spend the morning in Cascais. Walk the old town and the waterfront, then visit the Santa Marta Lighthouse Museum, a short and charming stop beside the sea. The Casa das Historias Paula Rego is a few minutes away and is one of the best small art museums in Portugal, with architecture worth seeing in its own right. After lunch, follow the coastal path to Boca do Inferno, where the Atlantic surges into a rock chasm, and return along the seafront for a swim or a coffee. If you still have energy in the evening, take the short train to Estoril, stroll through the casino gardens and have dinner by the sea.
Alternatives and swaps
If it rains on day one, move the garden-heavy plans to day three and swap in Queluz or Mafra, two grand palaces that are mostly indoors. If you are travelling with children, drop one of the palaces and spend more time at Guincho and the beaches. If you love history, add Mafra or the National Palace of Sintra, whose twin conical chimneys are the landmark of the village. If you have only two days, combine day two's morning with day one and keep Cascais for the second day.
Getting around
The train from Lisbon takes you to Sintra, and from Sintra a bus, taxi or tour reaches the hills. Between Sintra and the coast, taxis are the simplest way, although local buses also run and are worth checking if you are on a budget. Cascais is walkable, and the coastal path to Boca do Inferno is flat and easy. If you hire a car, use it for days two and three, but leave it parked on day one, because driving to Pena is not allowed and parking in Sintra is limited.
Where to stay
For the first night, Lawrence's Hotel or Tivoli Palacio de Seteais gives you atmosphere in Sintra and an easy start at Pena. For the coast, Farol Hotel and The Albatroz Hotel put you close to the waterfront, while Penha Longa Resort is a peaceful choice if you have a car. If you want a single base, Cascais gives you the best evenings, and Sintra is an easy day trip by taxi or train and bus.
A last tip
Resist the urge to add more. Three days feels generous only if you allow time to sit in a pastry shop, watch the surf or linger in the gardens. The best moments in this part of Portugal come from slowing down: mist moving through the pines, light on the ocean at the end of the day and the quiet of a forest convent after a morning of grand palaces.
