Casa das Tulhas is a covered market in the historic centre, occupying an 18th-century building that once served as a trading post for the colonial economy. Today it houses a mix of food stalls and craft vendors selling Maranhão specialities: dried shrimp, sesame products, vinagreira leaves (the key ingredient in cuxá), local spices, and artisan crafts.
The food section is particularly interesting — you can see and smell all the ingredients that define the regional cuisine and buy them to take home. The craft stalls sell ceramics, woven goods, lace, and Bumba Meu Boi-related items. It's a working market rather than a tourist market, and prices reflect that.