This is why I believe that every apartment door should have an intercom at the buzzer, failing that, a peep hole in your apartment door. Once at your front door, you should NEVER open the door to a stranger, makes no difference if you are home alone or not. A chain on the door doesn't really help. Best policy is just not to open the door.

I have square glass panes beside my door so I can check out everyone first. If I don't do it, I have dogs who will.

Do call the police and give a good description. It's too odd not to report.