I got a warning for cycling across the Zocalo on a busy morning.
there was nothing dramatic about it, but i was told very firmly by the female police officer who topped me that the Zocalo is only for pedestrians, so you better only walk there.
if you go to monte alban, be sure that you get back to the gift shop by 5 pm, when it closes. that is when the last bus leaves and also when the taxis leave. otherwise, you had better have a car if you want to get home again. there is nothing within a walkable distance.
Be careful of strangers offering assistance. My daughter was sexually assaulted by someone who she thought was offering assistance to her. A drug was put into her drink at a bar. She became tired, and sat down. Someone offered her assistance, and when assisting her back to her hotel, he sexually assaulted her. She was unable to protect herself due to the drugs in her system.
If you are travelling to Chiapas be advised to exercise extreme caution and avoid areas of political tension (particularly the highlands). There has been guerrilla activity in the states of Guerrero and Oaxaca. One should:
a) remain in known and well-frequented tourist areas;
b) avoid travel beyond resort cities; and
c) ensure they are in possession of valid photo identification (i.e. their passport).
México maintains strict controls on the importation of firearms. Handguns are prohibited,
and even hunting weapons require complex authorization procedures. They have ongoing
problems with drug traffickers, armed robbers and guerrillas. Possession of an undocumented weapon is taken very seriously.