Context: A staple for consumers in the city is the omnipresent "mercado". Every major neighborhood in the city has its own borough-regulated market, often more than one. These are large well-established facilities offering most basic products, such as fresh produce and meat/poultry, dry goods, tortillerías, and many other services such as locksmiths, herbal medicine, hardware goods, sewing implements; and a multitude of stands offering freshly made, home-style cooking and drinks in the tradition of aguas frescas and atole.

Question: What are the markets called that are located and run by the boroughs?
Answer: mercado

Question: What are some of the traditional drinks of Mexico City?
Answer: aguas frescas and atole

Question: What is the centerpiece of Mexico City's markets
Answer: mercado

Question: The author uses which adjective to describe the mercados?
Answer: omnipresent