Which historic site is notable in Saudi Arabia?

Al-Ula is a significant historic site in Saudi Arabia, recognized for its stunning landscapes and rich archaeological heritage. It is home to the ancient city of Hegra (Madain Salih), which features well-preserved tombs and monumental rock cut architecture that dates back to the Nabatean civilization, around the 1st century AD. Al-Ula is also part of a UNESCO World Heritage site, highlighting its importance and value in understanding the history of the region and the people who once inhabited it. The site showcases remarkable examples of ancient engineering and reflects the cultural interactions that occurred along the trade routes of the Arabian Peninsula.

In contrast, the other options pertain to historic sites located in different countries: Petra is in Jordan, known for its rock-cut architecture; the Great Wall is in China, recognized as a monumental fortification; and Machu Picchu is in Peru, famous for its Incan ruins. While all these sites are significant in their own right, they are not located in Saudi Arabia, making Al-Ula the correct choice for this question.