Thanks to the ever-generous Maria Kneusel, the series on Architectural terms got a big shot in the arm yesterday. Maria sent a link to a site called Fish Eaters, which has a nice overview of what the different parts of traditional church architecture are named. Along with the glossary, the site provides a plan view with the names. Now, we can see the narthex and the nave.
Holy Trinity isn’t really a cruciform (i.e cross-shaped) church, but it does help to see these terms laid out in plain view. See the full article “Inside your Church” for an interactive map linked to the definitions.
Inside your Church
Catholic vision assigns symbolic meaning to the various parts of the church building, as it does to pretty much everything else in the world. The roof symbolizes charity, which covers a multitude of sins; the floor symbolizes the foundation of faith and the humility of the poor; the columns represent the Apostles, Bishops, and Doctors; the vaulting represents the preachers who bear up the dead weight of man’s infirmity heavenwards; and the beams represent the champions of ecclesiastical right who defend it with the sword. The nave symbolizes Noah’s Ark and the Barque of St. Peter, outside of which no one is saved. The direction of the East represents the Heavenly Jerusalem, and the direction whence the Messiah will return in glory; West represents death and evil. (Catholic Encyclopedia)
UPDATE: More Architecture 101 here: