The main kalan (sanctuary), B1, was dedicated to Bhadresvara, which is a contraction of the name of King Bhadravarman, who built the first temple at My Son, combined with ‘-esvara’, which means Shiva. The first building on this site was erected in the 4th century, destroyed in the 6th century and rebuilt in the 7th century. Only the 11th-century base, made of large sandstone blocks, remains.
The niches in the wall were used to hold lamps (Cham sanctuaries had no windows). The linga inside was discovered during excavations in 1985, 1m below its current position.
B5, built in the 10th century, was used for storing sacred books and objects used in ceremonies performed in B1. The boat-shaped roof (the ‘bow’ and ‘stern’ have fallen off) demonstrates the Malay-Polynesian architectural influence. Unlike the sanctuaries, this building has windows and the Cham masonry inside is original. Over the window on the outside wall facing B4 is a brick bas-relief of two elephants under a tree with two birds in it.
The ornamentation on the exterior walls of B4 is an excellent example of a Cham decorative style, typical of the 9th century and said to resemble worms. The style is unlike anything found in other Southeast Asian cultures.
B3 has an Indian-influenced pyramidal roof typical of Cham towers. Inside B6 is a bath-shaped basin for keeping sacred water that was poured over the linga in B1; this is the only known example of a Cham basin. B2 is a gate.
Around the perimeter of Group B are small temples, B7 to B13, dedicated to the gods of the directions of the compass (dikpalaka).