Complex sentence: In 1991, the building manager gave the stone to the bicentennial resurveying team, who, in 2012, transferred the stone to the D.C. Office of the Surveyor, where it remains on display.
Split into simpler sentences: In 1991, the building manager gave the stone to a bicentennial resurveying team. In 2012, the stone was transferred to the D.C. Office of the Surveyor, where it remains on display.