Religious tourism is already big business in Saudi Arabia, but as the kingdom continues to implement Vision 2030, the tourism sector will receive millions in investment from the government. 

Some 18 million foreigners visited Saudi Arabia in 2016, but nearly all of these were participating in Umrah or Hajj.

Although pilgrimage to Islam's holiest cities will always be immensely important to the kingdom, there are many other historic sites that merit additional attention from tourists.  

Here's a look at some of the most fascinating and unique destinations the kingdom has to offer.

1. Al-Hijr

Al-Hijr Archaeological Site or Madâin Sâlih in Saudi Arabia definitely deserves more attention than it receives.

The Nabateans were an Arab people that once ruled large swaths of modern-day Saudi Arabia and the Levant, leaving impressive architectural remnants as a reminder of their civilization. Petra in Jordan is the more internationally famous Nabatean city, but it isn't the only impressive remnant of the ancient civilization

The ruins of Al-Hijr date from the first century B.C. to the first century A.D. It is the first UNESCO World Heritage site to be inscribed in Saudi Arabia. "With its 111 monumental tombs, 94 of which are decorated, and water wells, the site is an outstanding example of the Nabataeans’ architectural accomplishment and hydraulic expertise," according to UNESCO.

2. Khaybar

Located 153 km north of Medina, this historic oasis had a strong Jewish population until the 6th or 7th century A.D. Due to it's relatively lush setting and it's strategic location, Khaybar was an important stop on the incense trade route between the Levant and Yemen. 

3. Masmak Fort

Built around 1865, it was conquered in 1902 by Abdulaziz bin Abdul Rahman bin Faisal Al Saud. He went on to use it as his base to unite the present-day Kingdom of Saudi Arabia.

Now transformed into a museum, the fort has been called the "birthplace" of the modern Saudi nation. 

4. King Abdul Aziz Historical Centre

The origin of this historic district in Riyadh is the Murabba' Palace, which was built between 1936 and 1937 by King Abdul Aziz. Decades later, the old palace compound was restored and remodeled.  

Restoration was carried out in a way to preserve the original style and architecture. 

5. Ibrahim Palace

Located in Hofuf, the historic palace reveals secrets to life in Saudi hundreds of years ago. Work on the Ottoman complex began back in the 1500s with the Quba Masjid. During the next hundred years, the structure expanded to include the fort, a jail and a Turkish bath.  

6. Nasseef House

Situated in Souq Al Alawi in Jeddah, the house once belonged to a powerful trading family. The structure was completed in 1881.

It was later transformed into a library with some 16,000 books. Presently, it serves as a museum. 

7. Jawatha Mosque

Jawatha Mosque was the earliest mosque built in east Arabia around 629 AD. Although most of the mosque's original structure has disappeared, five small brick arches still remain.

According to legend, when the Hajr Al Aswad (Black Stone) was stolen from Mecca by the Qarmatians, it was kept in Jawatha for nearly 22 years.  

8. Al-Turaif District

As the first capital of the Saudi dynasty, the city was founded in the 15th century.The structures were built in Najdi architectural style, which is unique to the Arabian peninsula.

Tourists can discover the remains of palaces and the remnants of ancient urban life along the edge of an oasis.

9. Jubbat Ha'il

One of the largest and most significant archaeological sites in Saudi Arabia, Jubbat Ha'il is a series rock illustrations and inscriptions spread throughout Um Sanman Mountain and other neighboring mountains.

Two of the ancient inscription sites date back to the Mesolithic Period.

Recently, four of the rock inscriptions at Jubbah and Shuwaimis have been added to UNESCO’s World Heritage List.​​​​