The restoration of South Korea's number one national treasure Sungnyemun has been completed more than five years after a devastating arson attack.

Only the gates first floor and stone base were left after the fire. Restoration preparation alone took one and a half years. Master craftsmen recognized as intangible cultural assets participated in the project.

The restoration began in earnest in January 2010. Damaged parts of Sungnyemun were dismantled for a year. Pine trees known for their solidity were used to rebuild the largest damaged area of the national treasure.

Wood panels in good condition were reused, and more than 90 percent of the first floor was restored with recycled wood.

The five-year restoration project cost 27-billion-600-million won and a total of 15-thousand workers contributed.

The workers focused on restoring the ancient gate in its original form, based on records from the Joseon Dynasty. They even used traditional tools in an effort to truly replicate the cultural asset.

There are some differences, though. Large, new stone walls flank either side of the ancient gate. Japan removed the walls in 1907 during its colonial rule of the Korean Peninsula.

The ground of the ancient gate was also lowered, as depicted in the Joseon-era records.

The restored Sungnyemun will officially open to the public with a ceremony on Saturday.