Al Qal'a, Sohar, Oman

Sohar Fort rises above the southern part of the eponymous city, the third largest in Oman. Sohar is located 200 kilometers north of Muscat, about two hours from the UAE border. In the past, this city served as the main transit point in trade with China, connecting major trade routes through the Red Sea, India, and the Far East. Sohar is one of the oldest cities in the world. As early as the third millennium BCE, local inhabitants traded with the Sumerians, and two thousand years ago, Sohar was the capital of Oman. According to legend, this is where the legendary sailor Sinbad the Sailor, hero of the "One Thousand and One Nights," was born.

Unlike many other forts in the region, which traditionally have the color of the mud bricks they are made from—a color similar to desert sands—the walls and battlements of Sohar Fort are completely white.
Sohar Fort is currently a museum, but the original 10 km tunnel, which served as an evacuation route in case of siege, is still intact. The museum is dedicated to the important role the city played in ancient times in copper trade and its connections with the city of Canton in China.
The fort witnessed both the victories and defeats of Portugal in Oman. In 1643, Sohar was besieged by Imam Nasir ibn Murshid, who was later credited with expelling the Portuguese from the country.
Currently, the fort is undergoing restoration. Afterward, it is promised to be opened to tourists; visitors will be able to see the interior rooms as well.
Source:
https://archiqoo.com/locations/sohar_fort.php