Bangkok National Museum was pretty big altough during our time there were some halls which were being renovated. It has 12 halls with multimedia displays in English.
It is Thailand’s largest collection of local art and artefacts, founded by King Chulalongkorn in 1874 to exhibit the royal collections of his father King Mongkut. It is placed in former 18th century Wang Na Palace in Phra Nakhon.
The artefacts are dating from the Dvaravati, Srivijaya, to Sukhothai and Ayutthaya periods, on top of that the museum also displays collections of regional Asian Buddhist Arts such as Indian Gandhara, Chinese Tang, Vietnamese Cham, Indonesian Java, and Cambodian Khmer arts. Standouts of the Decorative Arts and Ethnological collection include Chinese weapons, precious stones, Khon masks, ceramics, textiles, and traditional musical instruments from Southeast Asia.
The museum has a funeral chariot hall displaying carriages used for royal cremations, it was one of the most glomorous halls I have ever seen in a museum.