Lisbon, the capital city of Portugal, is a beautiful city with a rich history, culture, and tradition. There are many free things to do in Lisbon that can make your trip enjoyable and affordable. Here are some of the best free things to do in Lisbon:

1. Explore Alfama: Alfama is one of the oldest and most charming neighborhoods in Lisbon. You can wander the narrow streets, admire the colorful houses, and enjoy stunning views of the Tagus River.
   
2. Visit Miradouro da Graça: Miradouro da Graça is a beautiful viewpoint that offers breathtaking views of Lisbon. You can take a picnic and enjoy the view while enjoying the local atmosphere.
   
3. Stroll through the historic neighborhoods of Baixa and Chiado: These neighborhoods are full of history, culture, and beautiful architecture. You can stroll through the streets, admire the buildings, and enjoy the local atmosphere.
   
4. Visit the Jerónimos Monastery: The Jerónimos Monastery is a beautiful example of Manueline architecture, and it's one of Lisbon's most impressive landmarks. The entrance to the church is free, and you can admire the stunning architecture.
   
5. Walk along the Tagus River: The Tagus River is the longest river in the Iberian Peninsula, and it's a beautiful place to take a stroll. You can enjoy the stunning views of the river, the city, and the boats passing by.
   
6. Explore the Belém Tower: The Belém Tower is one of Lisbon's most famous landmarks and is free to visit. It's a UNESCO World Heritage site and is a beautiful example of Portuguese architecture.
   
7. Visit the National Museum of Contemporary Art: The National Museum of Contemporary Art is free to visit on Sundays, and it houses a collection of Portuguese contemporary art.
   

These are just a few of the many free things to do in Lisbon. You can explore the city, discover its hidden gems, and enjoy the local culture without spending a dime.