Wat Rong Khun in Chiang Mai, Thailand is unlike any Buddhist temples in the world.
Prambanan is a Hindu temple in Central Java, Indonesia. The temple was built in 850 CE, and is composed of 8 main shrines and 250 surrounding smaller ones
No one knows exactly when the Shwedagon Paya (or Pagoda) in Myanmar was built - legend has it that it is 2,500 years old though archaeologists estimate that it was built between the 6th and 10th century.
Temple of Heaven is a Taoist temple in Beijing, the capital of China. The temple was constructed in 14th century by Emperor Yongle of the Ming Dynasty
Chion-in Temple [wiki] was built in 1234 CE to honor the founder of Jodo (Pure Land) Buddhism, a priest named Honen, who fasted to death in the very spot.
In the 19th century, Dutch occupiers of Indonesia found a massive ancient ruin deep in the jungles of Java. What they discovered was the complex of Borobudur, a gigantic structure built with nearly 2 million cubic feet (55,000 m³) of stones. The temple has nearly 2,700 relief panels and 504 Buddha statues.
The Harmandir Sahib (meaning The Abode of God) or simply the Golden Temple [wiki] in Punjab, India is the most sacred shrine of Sikhism.
The Temple of Srirangam (Sri Ranganathaswamy Temple), in the Indian city of Tiruchirapalli (or Trichy), is the largest functioning Hindu temple in the world.
Last but definitely not least is the largest temple in history and the inspiration to countless novels and action movies of Hollywood: Ankor Wat.