Pope Benedict celebrates Mass ad orientem
For today's liturgy in Rome commemorating the Baptism of the Lord was celebrated by the Holy Father in the Sistine Chapel. For today's liturgy, the high altar of the chapel was used, rather than a temporary, freestanding "people's" altar — as has been done in recent times. This is a significant development, for while the liturgical reforms of the Second Vatican Council did not abolish celebration of the Mass with the priest and the people in a common orientation to the "East," the practice has become so uncommon that many Catholics believe it was banned.
Amy Welborn writes about her tour of the Sistine Chapel, in particular about how the arrangement of the high altar has theological significance:
What I want to point out in relation to today’s Mass is something Liz showed us. There is nothing accidental about the interior decoration of the chapel, including Michelangelo’s Last Judgment fresco on the wall behind the altar. It is purposefully designed to provide a “space” for a large altar cross. The cross is set up to be directly below the figure of the Risen Christ - and these are the images which we - and the celebrant - face during Mass. To set up another altar in front of that and have the focus shift away does, indeed, violate the original intention of the space.
As with his motu proprio encouraging wider use of the traditional Latin liturgy, the Holy Father's celebration of the Mass today shows his commitment to emphasizing the continuity in Catholic thought and practice, in contrast to those who — erroneously — believe that Vatican II somehow inaugurated a "new church."