EARLY Liturgical Resources
A friend of mine called last week for the earliest sources on Christian baptismal practices, perhaps thinking that he would have to investigate expensive tomes available only at Some Fancy Library. Au contraire. The great thing is that the earliest (and most reliable) translations of descriptions of the really early Church practices are generally available over the public domain, online, as many of you know. This is where you go if you want to confute the heretics and point out what the early Christians REALLY thought and practiced about baptism, Eucharist, conversion, catechesis, etc.
I sent my friend to an excellent online resource for The Didache (ca A.D. 50, or within the lifetime of St. Paul). English Translation here.
There is also the slightly later Shepherd of Hermas documentation (ca A.D. 150)
... and if you want pictorial helps, just Google Images for "Ravenna" for some of our earliest intact basilicas, mosaics, baptistries, accoutrement, etc.