One of our favorites during our week-long visit to Santiago, Chile in October 2012 was the Mercado Central. Located on the northside of downtown Santiago overlooking the concrete-lined Rio Mapacho, the market is housed in a vast Victorian-age metal structure that was prefabricated in England and constructed in Santiago in 1868.
Mercado Central is primarily a fish market with an immense and varied array of fish and shellfish: Scallops, conger eel, turbot, calmar, albacore tuna, reinetas, clams, jibia (squid), picoroco (barnacles), black eel, red eel, salmon, shrimp, mussels, pejerrey (silverside fish), Spanish mackerel, stone crab claws, shark, sardines, and more. All fresh.
There are also a number of fish restaurants ranging from large centrally located ones that cater largely to tourists to small hole-in-the-wall cafes tucked in between stalls that serve a more local clientele. Both a ramble through the market and a meal at one of the many cafes is a must-do for any visitor to Santiago.