Porto is a beautiful city with plenty to see and do. Here's an ideal itinerary for 4 days in Porto:

Day 1:

• Start your day by visiting the iconic Clérigos Tower, which offers stunning views of the city.
• Next, head to the Livraria Lello bookstore, known for its beautiful architecture and as an inspiration for J.K. Rowling's Harry Potter series.
• After that, take a stroll through the charming Ribeira district, located along the Douro River. You can also take a boat tour along the river to see the city from a different perspective.
• End your day with a visit to one of Porto's famous port wine cellars, such as Taylor's or Sandeman, for a tasting and tour.

Day 2:

• Start your day by exploring the historic center of Porto, which is a UNESCO World Heritage Site. Visit the São Bento train station, the Cathedral, and the Palácio da Bolsa.
• Next, head to the Casa da Música, a modern concert hall designed by Rem Koolhaas.
• In the afternoon, visit the Serralves Museum of Contemporary Art and its beautiful gardens.
• End your day with dinner at one of Porto's many seafood restaurants, such as O Gaveto or Adega São Nicolau.

Day 3:

• Start your day by taking a day trip to the nearby town of Guimarães, known as the birthplace of Portugal. Visit the Castle of Guimarães and the Palace of the Dukes of Braganza.
• In the afternoon, return to Porto and visit the Mercado do Bolhão, a traditional market where you can find fresh produce, meats, and cheeses.
• Next, head to the Fundação de Serralves, a cultural center that hosts exhibitions, concerts, and other events.
• End your day with a dinner at one of Porto's many traditional restaurants, such as Casa Aleixo or A Cozinha do Manel.

Day 4:

• Start your day by visiting the Jardins do Palácio de Cristal, a beautiful park with stunning views of the Douro River.
• Next, head to the Casa do Infante, a museum dedicated to the history of Porto and its role in the Age of Discovery.
• In the afternoon, visit the Museu Nacional Soares dos Reis, which houses a collection of Portuguese art from the 19th and 20th centuries.
• End your day with a sunset walk along the Douro River, followed by dinner at one of Porto's many rooftop bars, such as Base or The Yeatman.