LOL, these guys saw us taking pictures from the terrace of the Palacio and gave us the thumbs up. They are a group of private security guards. There are many of these in Mexico. It's intimidating though, because they all look like the policia or federales. We walked past a man wearing a similar uniform, who was standing in the middle of the street and we thought he was a cop, but he was guarding a business. Very different.