Valencia is a beautiful city with a rich history and culture. Here's an ideal itinerary for 4 days in Valencia:

Day 1:

• Start your day with a visit to the Central Market, one of the largest and oldest markets in Europe. You can find fresh produce, seafood, meats, and other local products.
• After that, head to the City of Arts and Sciences, a futuristic complex of buildings designed by Santiago Calatrava. You can visit the Science Museum, the Oceanographic, or the Hemisfèric, an IMAX cinema.
• In the afternoon, take a stroll through the Turia Gardens, a beautiful park that used to be a riverbed. You can rent a bike or a scooter to explore the park.

Day 2:

• Start your day with a visit to the Cathedral of Valencia, a Gothic-style church that houses the Holy Grail. You can climb the Micalet tower for a panoramic view of the city.
• After that, head to the Lonja de la Seda, a UNESCO World Heritage Site that used to be a silk exchange. The building is a masterpiece of Gothic architecture.
• In the afternoon, visit the Mercado de Colón, a modernist market that has been converted into a shopping center. You can find gourmet food, fashion, and design shops.

Day 3:

• Start your day with a visit to the Albufera Natural Park, a wetland area located south of Valencia. You can take a boat ride to see the rice fields and the wildlife.
• After that, head to the beach of El Saler, a long and wide sandy beach that is perfect for swimming and sunbathing.
• In the afternoon, visit the historic neighborhood of El Carmen, a maze of narrow streets and colorful buildings. You can find street art, vintage shops, and bars.

Day 4:

• Start your day with a visit to the Museum of Fine Arts, which houses a collection of paintings from the 14th to the 20th century. You can see works by Velázquez, Goya, and Sorolla.
• After that, head to the Central Market again, this time for a food tour. You can taste local specialties such as paella, horchata, and buñuelos.
• In the afternoon, visit the Plaza de la Reina, a lively square in the heart of the city. You can have a drink in one of the terraces and watch the street performers.

I hope this itinerary helps you plan your trip to Valencia!