Quote Originally Posted by MacMillan of Rathdown View Post
In the lobby, concourse, or public areas of a building (such as a hallway, or railway platform) a gentleman leaves his hat on. When entering a "private" area, such as an office, the hat is then removed.
I would also submit that it is a show of respect to remove your hat when entering someones home, (another "private area" as you mentioned).

I'm glad to see this topic come up, this knowledge is sorely lacking in today's world. Along with walking on the "street side" of a lady when your on the sidewalk...things like that. This stuff is not taught anymore, that I know of....and it's a shame, really.