Several house-churches have survived from the time before Constantine. They began as homes, but were gradually given over to church use till they became full-time worship spaces. But the oldest known structure that seems to have been built as a church is the ruin at the Red Sea port of Aqaba in Jordan (known in antiquity as Aila). Pottery from the building’s foundations date the church to the late third or early fourth century. A bishop of Aila attended the Council of Nicaea in 325, suggesting that the place was already a bustling Christian center. When the site was excavated in the late 1990s, a churchyard cemetery was unearthed as well.

The Church at Aqaba is important for several reasons.

A few earlier churches are known, but these were originally built for other purposes, such as a house at Dura Europos in Syria that was converted into a church. Usually dated to ca. 230-240, it apparently went out of use when the city was captured by the Persians in 256. Mud-brick churches similar to the one at Aila are known from Egypt, but they are slightly later. Other early Christian churches, like that of the Holy Sepulcher in Jerusalem, originally erected ca. 325, have been in continuous use and rebuilt over the centuries, making their original architecture difficult to discern. The church at Aila was used for less than a century. Its latest coins date to 337-361, suggesting the church was a victim of an earthquake that, according to historical sources, devastated the region. The building was then abandoned and quickly filled with wind-blown sand, preserving its walls up to 15 feet in height.

See the church and the rest of the story at Archaeology magazine.