Cathedral, important thing in the Mexican capital Mexico City - Arabstoday Emperor Moctezuma must be having a little chuckle to himself in the Underworld.Five centuries after Spanish conquistadors condemned his entire civilisation to the history books - killing him in the process - the Aztec leader may finally be wreaking his much-promised revenge. Spain\'s blood-soaked arrival in Mexico in 1519 resulted in the eventual razing of Tenochtitlan - the capital of the Aztec Empire - to the ground two years later. Of course, the Spanish built a great metropolis of their own in its place. But as I look at the city’s cathedral, I can’t help thinking they failed somewhat in the area of town planning. Lurching drunkenly to one side, Mexico City’s biggest religious landmark - with her domineering twin towers and stark stone carvings - looks faintly amusing. It is almost as if she has grown tired of centuries standing to attention, and sunk down onto one hip to await her unavoidable fate. And she is not alone. All around the city’s main plaza – or Zócalo as it is known – glorious colonial buildings slump, slightly off-kilter, leaning against each other for support. Yes, Mexico City is sinking. That’s what happens when you take a valley full of lakes, fill them - as the conquistadors did - and build a city of 26 million people on top. Ironically, as the colonial buildings subside, public works programmes across the city keep turning up more Aztec artefacts, it is almost as if they are pushing themselves back to the surface to reclaim their city. Just to the side of the wonky cathedral in the Zócalo, construction workers first found remnants of Tenochtitlan’s Templo Mayor when a metro line was being constructed in 1978. Now, just below ground level, I can step back in time and wander the ruins of the Aztec city’s principal building. It is no longer a soaring 50ft temple painted red and blue, but faded paint on the bricks and stone carvings of gods with gloriously tongue-twisting names such as Coyolxauhqui, Huitzilopochtli and Quetzalcoatl, evoke an idea of how grand the city once was. This onion-layering of Aztec and Spanish is not just confined to the Zócalo. In nearby Tlatelolco Square the ruins of Tenochtitlan’s sister city and greatest ally stand overlooked by one of the oldest churches in the country. The marketplace in this square once dwarfed those in Istanbul and Rome – both cities of a similar size at the time – and it was here that young Emperor Cuauhtémoc – the last of the Aztec Emperors – made his final stand against the Spanish. After 80 days of warfare, Tenochtitlan fell and Cuauhtémoc was captured, tortured and killed. But remnants of the Aztec Empire aren’t all confined to ruined pyramids and bloodshed. In the south of the city the area of Xochimilco remains little changed from 500 years ago. Tenochtitlan was once an almost amphibious city, built across the valley’s lakes, with locals living in huts on stilts and paddling around waterways in canoes. The lakes may be long gone – thanks to the conquistadors’ hasty town planning – but come the weekend, little boats, called trajineras, still paddle the canals that line the remaining Aztec-style floating allotments known as chinampas. Head to Xochimilco on a weekend and the colourful boats are alive with chilangos (as Mexico City-dwellers are called) and tourists enjoying picnics, live Mariachi music and beer. Further to the north of the city, the Aztec links to one particular site take on a more controversial nature. The Basilica of Our Lady of Guadalupe is one of the most important Catholic sites in the world and saw more visitors last year than even the Vatican. Pushing through the maze of tarpaulin-covered stalls selling plastic statues of the Virgin of Guadalupe and Rosary beads of every variety, accompanied by booming music and Mexican soap operas playing on tiny portable televisions, I emerge into a strangely calm opening on Tepeyac Hill, crowned by two Basilicas – the 17th century sinking one and a sturdy new version. On this hill in 1531, a dark-skinned Virgin appeared to a converted Aztec called Juan Diego. To prove her existence she asked him to gather some roses growing on the hill and carry them in his tilma – a traditional cloak. When he unwrapped his cloak in front of the city’s bishop the image of the Virgin was imprinted on the material. That same tilma – uncorrupted by the passing of the years - hangs in the modern Basilica today and is seen as a miracle that hailed the Virgin as Queen of the Americas. But, as always in this complicated city of clashing cultures, there is another theory. It seems strange, some say, that the Virgin appeared on a hill which was associated with the Aztec mother-goddess Tonantzin, just when the Spaniards were trying to convert the locals... But as pilgrims from all over the Americas approach the Basilica, some making the agonising journey on their knees, others with tears of wonderment streaming down their faces, I find it hard not to be moved by the strength of faith placed in this humble hill and a simple picture on a cloth. Of course, Mexico City’s history goes beyond its Aztec-Spanish tug-of-war. It is also a metropolis famed for its spectacular public artworks, remnants from the days after the Revolution of 1910-1920 when murals were the only way for the illiterate masses to educate each other. As such, many public buildings are decorated with images of indigenous peasants rising up to demand equality and a right to land which was traditionally owned by the elite descendants of Spanish conquistadors. Great splashes of colour by Diego Rivera and José Clemente Orozco adorn the interior walls of the white marble Bellas Artes palace and the Palacio Nacional, depicting Mexico’s tumultuous history, traditional peasant life and their battle against the bourgeoisie. It is in Diego Rivera’s house, shared with his wife Frida Kahlo – the effervescent but troubled artist whose painful self-portraits reflect her struggles with a damaged body after a car accident – where Russian Marxist revolutionary Leon Trotsky stayed when he was exiled from his homeland. The striking and aptly-named Blue House quietly snuggles in the quaint village-like area of Coyoacan. It is a living museum dedicated to two of the country’s greatest artists, its walls decorated with self-portraits of striking Kahlo, iconic monobrow in place and hair scraped back into a sophisticated knot, and its calming courtyard a perfect escape from the often galloping speed of city life. After an alleged affair with Kahlo and a resulting fall-out with Rivera (somewhat understandable perhaps?) Trotsky and his wife left the Casa Azul and moved down the road to an altogether darker house, almost castle-like, but smaller and greyer. It too is now a museum, with an altogether more sombre ambience. Peering into a stark bedroom, I can still make out the bullet holes in the wall from a failed assassination attempt and the office where the revolutionary’s past eventually caught up with him in the form of a pick axe to the head. His tomb, a tall, overbearing stone monolith, decorated with a red flag, stands in the oppressively quiet garden. I can’t help thinking that – ironically – it is the kind of uniform structure his arch enemy Stalin would be proud of. Tragedy seems to seep from the very pores of this sinking capital, full of stories of fallen heroes and razed cities. Perhaps the Aztecs should have paid heed as they crossed the country in search of an eagle perched upon a cactus with a snake in its claw - the sign they had been told would pinpoint where to build their city. As they neared the valley of lakes they passed by the lofty temples of Teotihuacán, about 30 miles north-east of the present capital and still some of the best-preserved ruins in the entire country. The colossal Pyramids of the Sun and Moon and the eerily-named Avenue of the Dead (so-called due to the mistaken belief that the mini pyramids lining it were tombs) were built between 100 BC and 250 AD, making Teotihuacán the largest city of the pre-Columbian Americas, with experts believing more than 200,000 people once lived there. But nobody knows who they were exactly. Or what happened to make them suddenly disappear. All we know is that by the time the Aztecs passed through in around 1300 AD, there was nothing left but deserted temples and the city’s ghosts. Modern Mexico City is in every way the opposite of abandoned  Teotihuacán. It is vibrant and alive, full of colour and laughter, almost-unbearable traffic jams, mouth-watering street food and throbbing cantinas. But somehow I can’t help feeling it is a city equally haunted by its past.