The Architecture section on the Clipart ETC Web site offers over 1200 illustrations of architecture of various locations and time periods, including Byzantine, Egyptian, Greek, Renaissance, and Roman. Also available is a miscellaneous architecture gallery, and a visual dictionary, which shows the name and definition of various structural and artistic parts of architecture. Many of the line drawings in this collection can be useful when talking about church architecture and a maximum of fifty (50) clipart items may be used in any non-commercial, educational project (report, presentation, display, website, etc.) without special permission.
For additional resources on church architecture: Christianity and Architecture - Resources for Catholic Educators