How did a St Peter's basilica looks before 1506

If it reminds you of San Paolo fuori le mura, you are wright. San Pietro was a model for each church those days.
During the pontificate of Julius II basilica was torn down. Many people of the time were shocked, as the building represented papal continuity going back to Peter. Construction on the current basilica began on April 18, 1506 and was completed in 1626.