For being Spain's third largest city, Valencia is remarkably easy to get around. The old town combines endless picturesque buildings and old world charm with countless restaurants and bars all making for wonderful days wandering aimlessly. You can easily spend days just in old town, but here are a few highlights.
The central market is busy all day with locals shopping and tourists browsing. It's one of the best markets for both all set in a beautifully restored modernist building. Join the locals and sample some horchata, tapas, or pick up one of the pre-packed cups of ham and cheese.
The old silk market, La Lonja de la Seda, is not that remarkable on the outside but is definitely worth a short stop to see a shrine to business during Valencia's cultural and economic peak.
While we have seen more old catholic churches than there are verses in the Bible, we would have to say the self-guided tour of the cathedral is one of the most informative and enjoyable. Allow at least an hour since between the church and the museum there is a lot to see and learn. You don't get very close to the purported "holy grail", so if seeing is believing, you'll still have to take it on faith.
This is a place to ditch the map and explore the side streets [with all their wonderful graffiti] stopping along the way to enjoy a coffee, beer or wine.