What is Beth Sarim building built for? Is  it a monument  of sort, build by the prophet of Jehovah's Witnesses in remembrance of all the Old Testament prophet? I also understand that there are altars in this building in honour of each of the Old Testament Prophets.  I am not sure how far this is true and would like to know from someone, the beliefs that make this building so special.
J. F. Rutherford taught:


  that the faithful men of old will soon be resurrected by the Lord, be
  back on earth, and take charge of the visible affairs of earth. http://www.jwfacts.com/watchtower/bethsarim.php


These faithful men of old (probably Abraham and other patriarchs/prophets) would need somewhere to live and Rutherford set aside the house known as Bath Sarim to be that place:


  if and when the princes do return and some of them occupy the
  property, such will be a confirmation of the faith and hope that
  induced the building of Beth-Sarim. http://defendingjehovahswitnesses.blogspot.com.au/2009/11/beth-sarim.html


I think Bath Sarim is Hebrew for "House of Princes".

Rutherford's predictions of when they would return failed to come true, and the house has been sold (1948).


  The belief that the "princes" would be resurrected before Armageddon
  was abandoned in 1950 http://en.wikipedia.org/wiki/Beth_Sarim


I couldn't find any references to alters being built, or even a complete list of who the princes would be.