Generally, a temple was built by a king or ruler of a kingdom at that time for various purposes, for example as a place of worship, a residence for monks, a center of the kingdom or a place for religious teaching and learning activities. Information about the Kalasan Temple is contained in the Kalasan Inscription written in the year Saka 700 (778 AD). The inscription is written in Sanskrit using the pranagari script. The Kalasan Inscription explains that the religious advisors of the Syailendra Dynasty had suggested that Maharaja Tejapurnama Panangkarana build a sacred building to worship Dewi Tara and a monastery for Buddhist priests. According to the inscription of King Balitung (907 AD), what is meant by Tejapurnama Panangkarana is Rakai Panangkaran, son of King Sanjaya of the Hindu Mataram Kingdom.

Rakai Panangkaran later became the second king of the Hindu Mataram Kingdom. During the period 750-850 AD, the northern region of Central Java was controlled by kings from the Sanjaya Dynasty who were Hindu and worshipped Shiva. This can be seen from the character of the temples built in the area. During the same period, the Syailendra Dynasty, which was a Mahayana Buddhist school that was leaning towards the Tantryana school, ruled in the southern part of Central Java. This division of power influenced the character of the temples built in their respective areas at that time. The two dynasties were finally united through the marriage of Rakai Pikatan Pikatan (838 - 851 AD) with Pramodawardhani, the son of Maharaja Samarattungga from the Syailendra Dynasty.

To build a sacred building for Dewi Tara, Rakai Panangkaran bestowed the Kalasan Village and to build a monastery requested by Buddhist priests. It is estimated that the temple built to worship Dewi Tara was the Kalasan Temple, because inside this temple there was originally a statue of Dewi Tara, although the statue was no longer in its place. Meanwhile, what is meant by the monastery where the Buddhist priests were, according to speculation, is the Sari Temple which is indeed located not far from the Kalasan Temple. Based on the year of the writing of the Kalasan Inscription, it is estimated that 778 AD was the year the Kalasan Temple was founded.

According to several archaeologists, the Kalasan Temple has undergone three restorations. As evidence, there are 4 corners of the temple's foot with protruding parts. In addition, there are incisions made for restoration purposes in 1927 to 1929 by Van Romondt, a Dutch archaeologist. Until now, the Kalasan Temple is still used as a place of worship for Buddhists, especially the Tantrayana Buddhist sect and worshipers of Dewi Tara.

The temple building is estimated to be at a height of about twenty meters above ground level, so that the total height of the temple building reaches 34 m. The Kalasan Temple stands on a square base measuring 45x45 m which forms a corridor around the temple. On each side there are stairs going up to the temple veranda decorated with a pair of dragon heads at its feet. In front of the bottom step there is a stretch of floor made of stone. In front of the foot of the stairs, thin, smooth stone slabs with curved shapes are installed.

The overall temple building is rectangular in shape measuring 34 x 45 m, consisting of a main room in the form of a square and rooms that jut out in the middle of the four sides. The walls around the foot of the temple are decorated with kumuda motif carvings, namely kalpataru leaves coming out of a round vase.

Kalasan Temple has 4 doors located on the four sides, but only the doors on the east and west sides have stairs to reach the door and only the door on the east side is the entrance to the main room in the middle of the temple. Judging from the location of the main door, it can be said that Kalasan Temple faces east. Along the walls of the temple there are depressions containing various statues, although not all statues are still in place. Above all the doors and depressions are always decorated with Kala motif carvings. Right above the threshold, under the Kalamakara carving, there is a small decoration in the form of a woman sitting cross-legged holding objects in both hands. The niches on the left and right sides above the temple door are decorated with figures of gods in standing positions holding lotus flowers.

The upper body of the temple is in the form of a cube symbolizing the peak of Meru, surrounded by 52 stupas, on average, 4.60 m high. Along the boundary between the roof and the body of the temple is decorated with rows of dwarf creatures called Gana.

The roof of this temple is octagonal and has two levels. The first level is decorated with niches containing statues of Buddha Manusi Buddha, while the second level is decorated with niches containing statues of Dhayani Buddha. The peak of the temple is actually in the form of a stupa, but until now it has not been successfully reconstructed because many of the original stones have not been found. When viewed from the inside, the peak of the roof looks like a cavity from a circular arrangement of stones that narrows as it goes up.

The main room of the temple is square and has an entrance on the east side. Inside the room there is a tiered arrangement of stones that used to be a place to place the statue of Goddess Tara. It is estimated that the statue is made of bronze about six meters high. Attached to the west wall, behind the arrangement of stones there is a kind of altar of worship.