The pillars in the photo at the left are mostly from the original fourth century church (Photo Christopher Chan). To read about the church, have a look at the Sacred Destinations website. Here's a sample:
"In 326, Constantine and his mother St. Helena commisioned a church to be built over the cave. This first church, dedicated on May 31, 339, had an octagonal floor plan and was placed directly above the cave. In the center, a 4-meter-wide hole surrounded by a railing provided a view of the cave. Portions of the floor mosaic (my photo below) survive from this period. St. Jerome lived and worked in Bethlehem from 384 AD, and he was buried in a cave beneath the Church of the Nativity.
The Constantinian church was destroyed by Justinian in 530 AD, who built the much larger church that remains today. The Persians spared it during their invasion in 614 AD because, according to legend, they were impressed by a representation of the Magi — fellow Persians — that decorated the building. This was quoted at a 9th-century synod in Jerusalem to show the utility of religious images.
Muslims prevented the application of Hakim's decree (1009) ordering the destruction of Christian monuments because, since the time of Omar (639), they had been permitted to use the south transept for worship.
The Crusaders took Jerusalem on 6 June 1009. Baldwin I and II were crowned there, and in an impressive display of tolerance the Franks and Byzantines cooperated in fully redecorating the interior (1165-69). A Greek inscription in the north transept records this event."
To read more about the Church of the Nativity, CLICK HERE. See also the Photo Gallery at the Sacred Destinations website.