Wihan Thap Kaset, also known as Phra Rabieng Tin That or Phra Rabieng Tuean That, refers to the cloister or gallery that surrounds the base of the main stupa (Phra Borommathat Chedi).
The term "Thap Kaset" is an architectural term that refers to the surface or platform where Buddha images are placed, or to a structural boundary such as a cloister or gallery surrounding a sacred space. It is essentially equivalent to a wihan khot or a covered cloister that defines the sacred boundary.
Thus, the name Wihan Thap Kaset reflects its function: a surrounding cloister that marks the sacred perimeter of the main stupa.
