Final answer:
The architectural requirements of the early Christian liturgy were met by the development of the Christian basilica, such as Old St. Peter's Basilica in Rome.
Step-by-step explanation:
The architectural requirements of the early Christian liturgy were influenced by the shift in religious practices and the need for large interior spaces. These requirements led to the development of the Christian basilica, which became the core of Christian architecture. Old St. Peter's Basilica in Rome, along with similar churches, followed the plan of the Roman basilica but also added a transept to give them a cruciform shape, symbolizing the cross and the crucifixion of Christ.