On the southern outskirts of Mexico City lies Xochimilco, one of the last remaining sections of Lake Texcoco. It is referred to as "the floating gardens" because flowers and vegetables are grown on reed rafts floating on it. It is a very popular weekend excursion with the local city folk who take trips on these brightly decorated boats which are punted around the congested canals regularly bumping into each other. Canoes paddle between the boats selling tortillas, corn-on-the-cob and fruit to the passengers. Mariachi bands hitch rides on the boats offering to play their distinctive music. During our boat ride, we unfortunately got lumbered with an awful band - after paying them to play for us, most of the people in our group were considering paying them to stop!

Mexico City is surprisingly actually built on a lake. This dates back to around 1325AD when the nomadic Aztecs, guided by a premonition that their home would be where they saw an eagle perched on a cactus with a snake in its mouth, settled on an inhospitable, snake infested island in Lake Texcoco where they established their capital, Tenochtitlán. This lake was originally very large, covering most of a natural plateau in the mountains but, as the Aztec population grew, so did the island, initially with the Aztecs reclaiming land using dikes but more recently by the water level dropping due to the ever increasing population needing more and more water. With the lake almost dry now, the city has expanded to cover the entire plateau and is now suffering from serious subsidence: as the lake bed slowly dries out, the city sinks by 6" a year but unfortunately not evenly. We were shown many examples of buildings which were leaning over either because some of the foundations were on softer ground or because part of the building was heavier than the rest (like most churches).

The Basilica of Our Lady of Guadalupe. An example of Mexico City’s serious subsidence problem

Mexico's new Bassilica When the old bassilica became unsafe because of the subisdence, this modern looking replacement was built next door to it.

Around the time we booked this tour, we read some pretty scary advice for travellers to Mexico from the US State department's Bureau of Consular Affairs and the British foreign office. It warned against using the taxis that cruised the streets saying that they will first rob you and then hold you hostage until they have bled your credit cards dry. Similarly they warned against using cash machines for the same reason. The police aren’t supposed to be much help either as they are supposed to nearly all be corrupt - it said not to bother reporting a small theft as you needed to bribe them to get the relevant forms filled in. Finally, it warned against taking tour buses to the tourist sites as these were regularly ambushed sometimes even by the police! This was actually all pretty tame stuff compared with the travel advice for Guatemala (where half of our tour group continued on to). It implied that it was pretty rare to escape this country alive. Well, Mexico actually seemed to be a pretty safe place although there were a lot of armed guards around the place - particularly around jewellers and banks - and their cash machines were in cubicles which you could lock from the inside while you were using the machine. Our tour guide told us that there were problems around Acapulco but it was pretty safe where we were going.