Phra Thinang Kraison Siharat, commonly known as “Phra Thinang Yen” (the Cool Pavilion), is a small royal pavilion located on an island in the middle of Thale Chup Son, which was once a large reservoir supplying water to the city of Lopburi. The pavilion was constructed during the reign of King Narai the Great and was used as a seasonal royal residence during the cooler months, as well as a place for royal relaxation. Its location amid lush natural surroundings provided a cool, peaceful, and tranquil atmosphere.

The most remarkable historical significance of Phra Thinang Kraison Siharat is its role as the first astronomical observatory in Thailand. On December 11, 1685, King Narai the Great observed a lunar eclipse at this site together with French Jesuit missionaries. This event marked an important milestone in the introduction of Western scientific knowledge to Siam and reflected the peak of astronomical studies and diplomatic relations during King Narai’s reign.

Architecturally, the pavilion was constructed of brick and mortar, featuring a harmonious blend of traditional Thai and Western styles. Notably, the use of pointed arch windows and doorways demonstrates Western influence. Although only remnants of the walls and foundation remain today, the refined craftsmanship and advanced architectural concepts of the period are still clearly visible.

The surrounding area has been landscaped, with ponds reconstructed to recreate the historical setting, reflecting the time when the pavilion stood amid the vast waters of Thale Chup Son. The environment is shaded by ancient trees and remains far more tranquil than many other historical sites in the city center.

Phra Thinang Kraison Siharat holds a special appeal for historians, astronomers, and art enthusiasts who wish to study the integration of Thai beliefs with Western scientific knowledge. A visit to this site allows travelers to immerse themselves in the golden age of learning and openness that characterized Siam during King Narai’s era.

Visitors are warmly invited to retrace the history of Thai astronomy and experience the beauty enriched with knowledge at the historic site of Phra Thinang Kraison Siharat.

Private Car:

• Cross the Lopburi River bridge towards Thale Chup Sorn and head towards Ban Hin Song Kon; clear signs are posted along the route.

Motorcycle Taxi:

• Can be hired from the railway station or Lopburi city center, as it is close to other attractions in the area.

Songthaew:

• Take the Lopburi-Ban Berk line from in front of King Narai’s Palace and get off at the pavilion entrance.

Best Visiting Season: 

•  December is ideal for its cool weather and to commemorate the historical month of the lunar eclipse observation.

Preparation:

• The area is quite open; bring an umbrella or hat if visiting during midday.

Photography:

• The most popular shot is the reflection of the pavilion in the water; morning or late afternoon light is best for soft shadows and clear reflections.

Caution:

• Avoid climbing on the ancient brick ruins to help preserve the original structure from further damage.

Planning:

• This site can be visited immediately after the Din So Phong Village, as both are located within the Ban Hin Song Kon area.

Admission Fee

• Thai Visitors: 10 THB

• Foreign Visitors: 50 THB

Opening Hours

• Open Daily: 08:30 – 16:30

• Note: Morning visits are recommended to avoid the intense midday heat.