There is a very nice car & bus-free walk down the main street, Central Calle. It’s about 8 blocks long, no cars and no buses mean the diesel exhaust is a away from you. There are a couple plazas, the big Post Office, a plaza filled with pigeons and kids feeding them, and many shopping stores. Pedestrian only streets are always a draw, and I always found my way back here. The street right next to it had about 6 blocks of no cars too.
You guessed it - Avenida central is in the center of the city. It runs roughly east west and all the streets are numbered starting form here. It is a paved pedestrian mall for about 4 or 5 blocks in the center. Along the avenida you will find a lot of resturuants, banks clothing shops, and department type stores. In the street there are locals, street performers, hawkers of all sorts of useless things, many people sitting at small tables selling lotto tickets, I thought they were phone cards, but I am told it is for the national lotto. A block or so from the east end of the paved section is the Artists markets, past the west end is the cemtral markets.
From dawn until well into the evening, there are vendors selling their goods to the people walking up and down the Avenida Central pedestrian mall. Since cars are banned from the avenue, it seems at once both safer and cleaner. Certainly on Sunday much of San Jose comes out with their family for a walk and an ice cream.
For several blocks east and west of Plaza de la Cultura, Avenida Central is a pedestrian-only walkway, with shops and restaurants lining on both sides of the street. Both Ticos and tourists come here to shop and eat. You can find American fast-food restaurants such as McDonald's and Burger King, Tico fast-food chains, ice-cream parlors, sodas, bakery and supermarkets. There are also electronics, clothings, atheletic, book, crafts and department stores.
This is definitely the safest street of the whole San Jose, as police is present on every other block or so.