The oxen on the baptismal font by renier of huy symbolize

1. ambulatory2. apse 3. atrium 4. baptistery 5. catacombs 6. nave                7. porphyry 8.martyria9. mausoleum

4:  building used for baptismal rites and containing the baptismal font; sometimes merely a bay or chapel reserved for baptisms  

 3:  an enclosed area in the front of a house or building that allows the sunlight to permeate the space. Sometimes it can be open and sometimes covered by a skylight.  

 8:  shrines dedicated to those killed for their religion  

1:  an aisle circling the site of the choir or altar in a cathedral  

7:  an igneous rock distinguished by the a groundmass of minerals embedded with crystals  

 2 : a large niche, semicircular or polygonal in shape and usually vaulted, protruding from the end wall of a building in a Christian Church; it contains the altar  

 6 : the central approach to the high altar. (from Latin navis meaning "ship," suggested by the keel shape of its vaulting)  

9 : a large burial chamber, usually above ground  

 5:  underground burial sites  

Explanation: