<a href="http://en.vietnam.com/central-vietnam/other-places-of-interest/hai-van-pass.html" rel="noreferrer nofollow">Hải Vân Pass</a> (Hải: ocean, Vân: cloud) is a scenic pass on the road from Da Nang to Hue, on the National Road 1A in Vietnam.

During the Nguyen Dynasty (1802-1945), the pass was an important military site and served as a protection for the Hue Royal Citadel. People then had to submit the necessary papers to be allowed through the guarded gate.

Under the rule of the second emperor of Nguyen Dynasty King Minh Mang in 1826, French troops built a blockhouse, named Don Nhat, to protect the Hai Van Pass. This gate could not be seen as you journey on top of the pass, now taking the form of a brick gate covered with moss. It stands 10 meters high with walls as thick as five meters. It faces Thua Thien-Hue Province, and is inscribed with three words “Hai Van Gate” in Han script.

On the other side, the gate is engraved with: “The most grandiose gateway in the world”, written in Han script. These words were said by King Le Thanh Ton (1442-1497) when he visited the site. Source: <a href="http://en.vietnam.com/central-vietnam/other-places-of-interest/hai-van-pass.html" rel="noreferrer nofollow">en.vietnam.com</a> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - <a href="http://en.wikipedia.org/wiki/H%e1%ba%a3i_V%c3%a2n_Pass" rel="noreferrer nofollow">The Hải Vân Pass</a> ("ocean cloud pass"), is an approximately 21 km long mountain pass on National Road 1A in Vietnam. It traverses a spur of the larger Annamite Range that juts into the South China Sea, on the border of Đà Nẵng and Thừa Thiên-Huế Province, near Bach Ma National Park.

Its name refers to the mists that rise from the sea, reducing visibility. Historically, the pass was a physical division between the kingdoms of Champa and Dai Viet. The twisting road on the pass has long been a challenge for drivers traveling between the cities of Huế and Đà Nẵng. Since the completion of Hai Van Tunnel, traffic flow and safety have improved.

<a href="http://en.wikipedia.org/wiki/H%e1%ba%a3i_V%c3%a2n_Pass" rel="noreferrer nofollow">The Hải Vân Pass</a> crosses over a spur of the Trường Sơn (Annamite) Range that emerges from the west and juts into the South China Sea, forming the Hải Vân Peninsula and the adjoining Son Tra Island. The pass, which once formed the boundary between the kingdoms of Đại Việt and Champa, also forms a boundary between the climates of northern and southern Vietnam, sheltering the city of Da Nang from the "Chinese winds" that blow in from the northwest. During the winter months (November–March), for instance, weather on the north side of the pass might be wet and cold, while the south side might be warm and dry.