The grand Zocalo was the agora of the Templo Mayor de Tenochtitlan. New palaces and temples -this time christian- were built, on the ruins of the old palaces and temples. Markets remained markets. The city continued to grow. Great mansions, shops and schools were erected, but fortunately the Center continued to be both historic and monumental. Today the elegant palaces are museums, hotels and shops.
The ancient Tenochtitlan struggles to rise from the rocks and can be seen by the Cathedral, at the National Palace and wherever you want to dig inside the Zocalo. Mexico's history is told by Diego Rivera and by old stones. The fact that Mexico is sitting on a lagoon is obvious just by watching so many tilted buildings defying gravity. However, the center is not sinking: it is moving, re-accomodating itself.
The Historic Center is still the center of the city. Residents continue to come to celebrate, to protest, to have fun, to shop and stroll. In comparison to any other metropolis, the extraordinary thing in Mexico City is that everything is authentic. What you see is what you get. No illusions or delusions for tourists. Passersby are not extras. San Judas is on the street, as is the Santa Muerte, the women selling tlayudas and stew tacos, the shoe shiners, the cantinas, the popular markets, the wrestling and the scribes. Everything is real, everything is commonplace. The center will always be the center.
What you are walking through. The Historic Centre has been a UNESCO World Heritage Site since 1987, in the same inscription as Xochimilco, and it holds the densest concentration of museums, churches and listed buildings in the country. Its appeal is that it is built in layers on the same ground: the Templo Mayor and the ceremonial precinct of Tenochtitlan, the viceregal city raised on its stones, the Porfirian palaces of the 19th century and the 20th-century buildings that completed the ensemble. That is why you walk it: within four blocks you change era several times.
How to structure a visit. The natural anchor is the Zócalo, with the Metropolitan Cathedral, the National Palace and the Templo Mayor on the same corner. Clear routes lead out from there: west along Madero —pedestrianised— to the Torre Latinoamericana, the Palacio de Bellas Artes and the Alameda Central; north along Donceles and Santo Domingo, with its arcade of public scribes and second-hand bookshops; south to Regina and San Jerónimo, also pedestrian, with cafés and bars; east to La Merced and its market, the loudest and most working-class part of the district. Calle Tacuba concentrates small museums, including the Perfume Museum, the Army Museum and the National Art Museum.
Practical advice. Most museums close on Mondays: if you only have one day, do not make it Monday. Mornings are best for photographs and for entering churches without crowds; from mid-morning the Centro fills with street vendors and tour groups. Watch your belongings in the crush around the Zócalo, Madero and La Merced, and use a ride app at night. Check whether an event or a protest is scheduled on the Zócalo the day you visit, as access gets closed off.
Getting around. Four metro lines serve the district: Zócalo-Tenochtitlan and Allende (Line 2), Bellas Artes (Lines 2 and 8), Pino Suárez (Lines 1 and 2), Isabel la Católica and Salto del Agua (Line 1), San Juan de Letrán (Line 8). Inside the perimeter everything is done on foot: many streets are pedestrianised or traffic-restricted, and a car is a liability.