Most interesting post by Msgr. Charles Pope that looks at worship in house churches in the first centuries of the Church. Not as informal as those trying to recover New Testament style worship would have us believe.
As you may know, the Catholic Faith was illegal in the Roman Empire prior to 313 AD, when the Emperor Constantine issued the Edict of Milan permitting the Christian Faith to flourish publicly. Prior to that time, Church buildings as we know them today were rare—Mass was usually celebrated in houses.
Now be careful here; these “houses” were usually rather sizable, with a central courtyard or large room that permitted something a little more formal than Mass “around the dining room table.” I remember being taught (incorrectly) that these early Masses were informal, emphasized a relaxed, communal quality, and were celebrated facing the people. Well, it turns out that really isn’t true. People didn’t just sit around a table or sit in circle—not at all. They sat or stood formally, and everyone faced in one direction: east.