In Mexico City, they are black markets where they sell counterfeit items, such as fake Raybans and Dr. Dre headphones, along with other stuff. People have to be careful when selling counterfeit items, as the police patrol almost everywhere. They often have a person who stands and watches for the police and whistles if they see one coming, the vendors items on a sheet that can be quickly pulled up and looks like a normal bag when the police arrive. you can buy almost anything at the black markets, watches, shoes, and some sell knives, which I would have gotten one if they were allowed in the UK. On Sunday there is a massive antique market at Lagunilla, and next to it is a black market that stretches on for blocks and blocks. You can buy almost everything in this market if you look hard enough. The market is hot and crowded, and tarps cover everything. People walk down the aisles selling frozen fruit and drinks, and vendors play the music they are selling loudly through blown speakers. It is a very nice and fun just to explore and look at all the things they have for sale.