While historical records say that Sri Jagannath temple is about one thousand years old, Puranas connect its inception to the Satya Yuga. The description of the Sri Jagannath temple built in that period portrays a monument that is very different from that of the existing temple. So the present temple is evidently not the same as the one built in Satyayuga.
The scriptures do not mention anything about how long the first temple lasted, nor do they relate anything regarding the time or the building of the second or the succeeding ones [Since it is impossible to guess a figure of the time gap between the two periods, it will be erroneous to say that the present temple is the second one. The possibilities of the construction and end of several or even numerous temples cannot be eliminated].
The art work of the present temple is certainly admirable. It’s a pity that the information regarding the grandeur of the temple(s) built in the interim is not found in any of the mythological or historical writings. However, a description in Skanda Purana gives a brief account of the magnificent artwork of the first Sri Jagannath temple and dedication that made it possible.
The Purana relates the story of the king Indradyumna who, intently seeking to see Lord Vishnu, performed 1000 Ashwamedha Yajnas flawlessly and was blessed to have a vision of him. Thereafter, he heard a divine command from the blue unknown as to the construction of a special temple where the idols of Lord Jagannath, Balabhadra and Subhadra were to be installed.
As per the instruction, he was to construct a temple on a big plain area on the Nilachal [Blue Mountain] which was 100 hands [approximately 100 feet] away from the northwest of Kalpa Brikshya and to the north of Lord Nrusimha.
Leading architects were assigned to construct the temple with utmost sincerity and under strictest supervision. In a short period the monument became so high that the top was almost out of sight. All the kings of that time voluntarily contributed their bit to the making of the architectural wonder. Its height touched the skies and width extended in all the four directions.
The temple walls were studded with gold at places and were ablaze with various kinds of precious stones. The crystals fixed on it created the illusion of white clouds in autumn and the black stones of the black. Complying with the principles mentioned in the temple architecture, special stones were placed to protect the temple from lightening and other natural threats [the stones were earned by the king himself by doing righteous deeds].
This mammoth task finally came to an end and the king, pleased at its successful completion, told Maharshi Narada that the divine favour had helped him to accomplish such a task that was impossible for both gods and demons.
The temple and the characters associated with it though appear to be real; the evidences to prove their authenticity are missing. They still seem and will continue to be as mysterious as Lord Jagannath himself until some astonishing archeological discovery [like submerged Dwarka and Ram Setu] proves otherwise.