Mercado Cuatro is Asuncion's largest and most chaotic market, sprawling across several blocks of the city and selling everything from fresh produce and medicinal herbs to electronics, clothing, and religious items. It is genuinely overwhelming — the crowds, the noise, the smell of grilled meat and spices — and it is the most visceral glimpse you will get of everyday Paraguayan commerce and life.
The market is busiest in the morning and tails off by early afternoon. Come for the atmosphere rather than any specific purchase, though the produce section is good if you are self-catering. Keep a close eye on your belongings; pickpockets operate here. The area around the market is one of the most densely populated parts of central Asuncion and is worth wandering even if you don't go into the market itself.