The ancient Yom Kippur Temple service took place in the Temple in Jerusalem.
While the Jerusalem Temple stood, the High Priest performed a special annual service on Yom Kippur, the Day of Atonement. The ritual is described chiefly in Leviticus 16 and involved sacrifices, confessions, incense, and blood rites intended to atone for the people and purify the sanctuary.
The service was exceptionally restricted. Yom Kippur was the only day on which the High Priest entered the Holy of Holies, the innermost chamber of the Temple. He wore special white linen garments for this part of the ceremony and also supervised the ritual involving two goats: one was sacrificed and the other became the scapegoat sent into the wilderness.
A common mix-up is confusing Jerusalem with Mount Gerizim. Mount Gerizim was the sacred center of the Samaritan community, while Jewish Temple worship centered on Jerusalem. The Temple service ended after the Second Temple was destroyed by the Romans in 70 CE, but its order remains central to the Avodah passage recited in many Yom Kippur prayer services.