Syria's church is regarded as the oldest in the world, and Dura-Europos is a significant historical site.

Dura-Europos Church in modern-day Syria is widely considered to be the oldest house church in the world. Today, the ancient church only remains in ruins.

Syria's church is regarded as the oldest in the world, and Dura-Europos is a significant historical site.

The Dura-Europos Church is regarded as the oldest in the world.

More precisely, because Dura-Europos was first built as a house before being converted into a church, it is regarded as the earliest Christian house church in the world.

A house church is characterized as a gathering place for worship in a private residence.

Some historians disagree that Dura-Europos should have the same status as it does because it was not built as a church in the first place.

That said, there are still many sources that credit Dura-Europos with the "world's oldest" title. The church is named the oldest church building by Guinness World Records. 

The church was built in the city of Dura-Europos, near the village of Salihiyah in modern-day Syria. The church was built somewhere between 233 and 256 AD, according to Christianity.com

In the 1920s and 1930s, a group of American and French archaeologists, led by Yale University and the French Academy of Inscriptions and Letters, excavated the area where thousands of artifacts, including frescoes, were unearthed. Fresco painting is a "method of painting water-based pigments on freshly applied plaster, usually on wall surfaces," according to Britannica. 

Excavating the city led to the discovery of an unearthed synagogue, a Christian building and Mithraeum, plus over 12,000 artifacts that are preserved at Yale University today, according to the Ivy League's website. 

The paintings found during excavation are among the artifacts that now live at Yale University and are considered some of the oldest Christian paintings ever discovered.

One of these is a piece that was found in the baptistery, which was discovered in three fragments. 

Today, the church is left in ruins in an area controlled by ISIS, according to Christianity.com.

As for the oldest church in the United States, many sources consider it to be San Miguel Chapel in Santa Fe, New Mexico.  

The Catholic Church dates back to 1610. The chapel has been reconstructed many times since it's creation and is still in operation today.