Complex sentence: Sanam Luang has been used since the time of King Rama I. It was the site of royal ceremonies and functions, including the cremation of the Prince of the Palace to the Front, who was Rama I's brother.
Split into simpler sentences: Sanam Luang has been used since the time of King Rama I. It was the place for royal ceremonies and functions. Including the cremation of the Prince of the Palace to the Front, who was Rama I's brother.