http://revach.net/article.php?id=4259

Section: Stories   Category: Gadlus
Rav Chaim Soloveitchik's Brisker Door
Rav Chaim Brisker was an incredible Ba'al Chesed.  His home was totally hefker to all those who wanted to enter.  People ate his food, took away his seforim, and even slept in his bed leaving him nowhere to sleep some nights.  His concern for other was so great that it didn't dawn on anyone that they were inconveniencing him, and they probably weren't.  His house was the local hangout for anyone who had no where to go.

Someone once asked why he had a door on his house if it performed no function whatsoever, since it was always open.  The answer was obvious.  According to one Dei'a, in order to put a Mezuza in a doorway it needs a to have a door on it.  The door is there just to make sure that the Mezuza is 100% L'Chatchila.  Why else would someone have a door?