Hima in the southwest is home to rock inscriptions that are thousands of years old.
A sixth site in Saudi Arabia has been added to UNESCO's world heritage list.
The UN organisation announced on Saturday that it had added Hima, in the Gulf state's southwest.
The site is home to one of the largest rock art complexes in the world.
The region features more than 34 separate sites including rock inscriptions and wells along the route of the ancient Arabian caravans.
Al-Ahsa Oasis, an Evolving Cultural Landscape, was the last site added the heritage list in 2018, according to UNESCO.
Hima was a conduit for caravans on the trade and hajj routes to and from the southern parts of Arabia.
"People who passed through the area between pre- and post-historic times have left behind a substantial collection of rock art depicting hunting, wildlife, plants, symbols, and tools used at the time, as well as thousands of inscriptions," the Saudi official news agency SPA said.
The site covers 557 square kilometres.
"Travellers and armies camping on the site left a wealth of rock inscriptions and petroglyphs through the ages and until the late 20th century, most of which are preserved in pristine condition," UNESCO said.
"Inscriptions are in different scripts, including Musnad, Aramaic-Nabatean, South-Arabian, Thamudic, Greek and Arabic."
The wells in the area are more than 3,000 years old and were considered a vital source of fresh water in the vast desert of Najran province, SPA said.
"They still serve fresh water to this day," it added.
Other UNESCO sites in Saudi Arabia include rock art in the Hail region and historic Jeddah.
In 2019, Riyadh announced that for the first time it would grant tourist visas for those wishing to visit Saudi Arabia.
Previously, the country was open only to businessmen and Muslim pilgrims visiting the holy cities of Mecca and Medina.
The Saudi leadership wants to increase the share of tourism in the kingdom's GDP, which right now is mostly dependent on oil. But a host of setbacks including the killing of journalist Jamal Kashoggi and consequent criticism have slowed down Saudi reforms.
Saudi Arabia now has as many heritage sites as Pakistan. Turkey has 18 sites in the UNESCO heritage list.