12 stairs were located at the front of the Ulam and each stair was one half a cubit high. * The priests stood on these stairs at the conclusion of the daily Tamid service - the burnt offering - and bestowed the Priestly Blessing upon the people. (Source: Tamid 7:2). 
The Entrance to the Ulam
Contents:   Part I,    Part II,    Part III,    Part IV,    Part V,    Part VI,    Part VII