There is so much sightseeing to do inside and outside Oaxaca that you have to be sure to allow some idle time for enjoying the zócalo. In the traffic-free square, you can relax while getting a feel for the town and a good glimpse of Oaxacan society. I recommend going in the late afternoon and taking a seat at the outdoor cafe with the best view of the cathedral. You can get a beer or order a bowl of the traditional drink of Oaxaca: chocolate. The afternoon light filters through the shiny green leaves of the laurel trees, heightening the color of the cathedral's green stone. As dusk comes, a small drill corps enters stage left and performs a flag-lowering ceremony with much pomp and circumstance. Then the marimba or the municipal band usually strikes up in the central bandstand.
The city contains museums worth visiting, some interesting churches, and colorful markets. Outside town are the famous ruins of Monte Albán and Mitla and area villages known for their arts and crafts.
Besides visiting the places listed, try to get to the Casa de Cortés, which houses the Museo de Arte Contemporáneo , and the former convent of Santa Catalina, home of the Hotel Camino Real.
