Yes, you must take off your hat no matter how cold or uncomfortable it is, or how smashed and ugly your hair looks. If you don’t, Russians will think that you are an uncultured lout. But the interesting issue is why. And here theater ushers, museum guides, and other ticket-takers at the door who are huffing over foreigners’ lack of manners might not even know why it’s considered to be so uncouth. It’s a pre-Revolutionary habit, from the days when an icon was placed on the wall of every entrance, be it an izba (peasant hut), manor house, palace, food shop or business. So when people entered, the first thing they saw was the icon. Men took off their hats and made the sign of the cross. Today there aren’t icons in the entrances to most buildings, but the custom that men must take off their hats inside has remained in the culture. So take off those baseball caps as soon as you step through any doorway.