We have just returned from a holiday in Lisbon with our kids aged 5 and 7. It is such a great city for a family to explore (although a little expensive). Here are our highlights:

Castelo - this is where you find the Castelo de São Jorge which has great views across the city and the kids loved exploring it - they sat on the cannons, climbed the towers, viewed the archaeological site, and got a guided tour across the city via the camera obscura. We were even joined by peacocks whilst we ate lunch!
Belém - this is a lovely area just outside the city centre (you can get there via train, bus or tram) where the kids roamed by the waterfront (we also tried the electric scooters), climbed up the Tower of Belém, took a trail around the Art Museum (Museu Coleção Berado with a collection to rival Tate), and marvelled at the ornate Jerónimos Monastery, before we ended the day tasting the Pastéis de Belém!
Cascais - this seaside town is a 40 minute train ride along the coast where we climbed to the top of a lighthouse, visited the spectacular orange building and paintings in the Paula Rego Museum The House of Stories, and ran around in the nearby Parque Marechal Carmona (where in summer there is a petting zoo). Of course there was the beach as well, where the kids ate icecreams, built sandcastles and splashed in the waves!
Parque das Naçeõs - this area was so good for the kids we came twice! Arriving at Oriente station we checked out the street sculptures (by Anthony Gormley, Jorge Vieira and others), then took a cable car along the waterfront to the Oceanário. If you think you’ve been to an aquarium before you’ve not been to one this enormous! A giant central tank is surrounded by a number of zones featuring animals and fish from different climates - our favourites were the playful sea otters and the waddling penguins (one was called Oliver Twist!) We returned a few days later to experience the nearby science museum Pavilhão do Conhecimento (The Pavilion of Knowledge) - two massive floors packed with interactives and the Dóing area where you could ‘make’ and ‘tinker’. It was loads of fun and very educational!

In addition to these highlights, roaming around the city was a big hit with the kids - taking trams and furniculars to viewpoints as well as a boat across the River Tagus. And our fussy little eaters even enjoyed some of the ‘petiscos’. We hope to go back one day - as my 5-year-old says “I love Lisbon”!