You can read a brief detail of this temple from the articles of the eminent historian namely Micheal W Meister. As per his studies the temple was never completed and the king who built this temple was Yasovarmam who was the contemporary of Kashmiri King Lalitaditya in the eight century. This temple is a proof that Mountain Kings acquired a great deal of power at that juncture and their kingship is known through these type of monuments. However, the earthquake in 1905 that shook the whole Himachal Valley had done a great deal of damage to this temple.
Towards the beginning, the temple was believed to be Vishnu oriented by the Indian Historians as the sanctum holds the idols of Lord Rama, Godesses Sita and Lord Laxmana. Later after a brief research, the Indian Historians agreed and resolved that this is a Shaiva based temple dedicated to the Lord Shiva. As per the report, it contains fifteen shrines of Gods.
This temple is carved out of a monolithic rock and built with Nagara Style of Architecture. The prominent features of Nagara style temple includes Shikaras (Spiral roofs), Garbhagriha (sanctum) & Mandap (pillared hall).
I would not go in too much detail and enclose here the pictures and try to give you a slight glimpse of the temple architecture and the area around it.