Long Cheng, also known as Long Tieng, Long Chieng, or Long Tieng Valley, is one of the most fascinating and historically significant destinations in Laos. Hidden deep within the mountains of Xaysomboun Province, Long Cheng was once known as "The Most Secret Place on Earth" and served as the center of the CIA's covert operations during the Secret War in Laos from the 1960s to 1975. Today, visitors can explore this remote valley and uncover a remarkable chapter of Southeast Asian history while enjoying the stunning mountain scenery that surrounds the former secret city.

Before 1962, Long Cheng was a sparsely populated valley with only a handful of inhabitants. During the Secret War, the CIA transformed it into a massive military and intelligence base supporting Hmong forces under General Vang Pao. By the late 1960s, Long Cheng had grown into a hidden city of approximately 40,000 people, making it the second-largest city in Laos at the time—despite never appearing on official maps. It became one of the busiest airbases in Southeast Asia, with hundreds of flights arriving and departing daily.

The valley served as the headquarters of the Hmong "Secret Army" and played a crucial role in military operations during the Vietnam War era. Surrounded by steep limestone mountains and rugged terrain, Long Cheng was strategically positioned to support operations throughout northern Laos. The area witnessed intense battles, particularly in 1971–1972, before eventually being evacuated in 1975 as communist forces gained control. Thousands of Hmong soldiers, civilians, and CIA personnel were airlifted from the valley during the final evacuation.

Today, many traces of this extraordinary history remain. Visitors can still see portions of the original runway, old military structures, former airbase facilities, bunkers, and remnants of the infrastructure that once supported the secret city. The former residence area associated with General Vang Pao and various military positions can still be identified throughout the valley. Although much of the area has returned to peaceful rural life, the historical significance remains evident.

Beyond its wartime history, Long Cheng is surrounded by breathtaking mountain landscapes, mist-covered valleys, and traditional Hmong communities. The journey to the valley offers spectacular views of Xaysomboun's rugged terrain and provides visitors with insight into the culture and traditions of the Hmong people who continue to live in the region. The combination of dramatic history and beautiful scenery makes Long Cheng one of the most unique destinations in Laos.

As access restrictions have gradually eased in recent years, Long Cheng has become increasingly popular among history enthusiasts, photographers, and adventurous travelers seeking to understand one of the least-known chapters of the Vietnam War. Visiting the site provides a rare opportunity to explore a place that remained hidden from the outside world for decades.

Opening Hours

  • Open daily: 08:00 AM – 05:00 PM
  • Best time to visit:
    • November to February for cool temperatures and clear mountain views.
    • Early morning for mist-covered valley scenery.
    • Dry season (November–April) for easier road access.

Highlights

  • Former CIA secret city during the Secret War.
  • One of the most historically significant sites in Laos.
  • Former headquarters of General Vang Pao and the Hmong Secret Army.
  • Historic runway and military infrastructure remnants.
  • Stunning mountain valley scenery.
  • Rich Hmong cultural heritage.
  • Fascinating Vietnam War and Cold War history.
  • Excellent photography opportunities.
  • Remote and authentic travel experience.
  • Unique combination of history and natural beauty.

Visitor Tips

  • Hire a knowledgeable local guide for historical context.
  • Bring identification, as access procedures may occasionally vary.
  • Wear comfortable walking shoes.
  • Carry drinking water and snacks due to limited facilities.
  • Respect local communities and military areas.
  • Bring a camera for both historical sites and landscapes.
  • Check road conditions before traveling during the rainy season.
  • Allow a full day to explore the valley and surrounding viewpoints.

Location

Long Cheng is located in Longchaeng District, Xaysomboun Province, approximately 130 km northeast of Vientiane. Access is typically by road through the mountainous regions of Xaysomboun Province.