Pope Benedict XVI starts the second full day of visit to the United States with a mass at Nationals' Park baseball stadium in Washington, D.C.. It starts at 10 a.m., but the stadium is already filling up.

The outfield is home to a to very large white and gold superstructure over the moden altar where Benedict will celebrate the mass, and behind the altar there's a large and very traditional wooden crucifix. The structure appears to offer some protection against rain, but that won't be necessary today: There's not a cloud in sight - just security helicopters whirling over the stadium.

The crowd, which is expected to fill all the 47,000 available seats, is being treated to the music of live choirs interspersed with videos generated by various dioceses and archdioceses greeting Benedict. The Philadelphia Archdiocese's video flashed on the Jumbotron about 20 minutes ago: It features lots of cute kids standing in front of Philadelphia landmarks, but we can't hear it in the glass-enclosed press gallery.

I wonder if the Washington Nationals will keep the white picket fence and shrubs planted around the baselines. Might get in the way of an infield double.