Drunken tourists on Friday trespassed on a 1,400-year-old astronomical observatory named Cheomseongdae, the oldest in Asia, in the historic city of Gyeongju.
The three university students were arrested after they climbed Cheomseongdae to take selfies around midnight.
The observatory lists 205 mm to the north and around 5 mm to the west. Safety concerns were raised after a series of minor earthquakes in Gyeongju in September of last year when the upper part of the observatory was pushed 38 mm further northward.
There are two rows of fences around Cheomseongdae to keep visitors away, but they are only 30 cm high and practically anyone could hop over them if they wanted to.
Just three years ago, the fence was 1 m high, but Gyeongju city lowered it to 30 cm amid complaints from tourists that the fence made it difficult to take photos. A Gyeongju city official said, "It was a necessary measure to promote tourism."
During the day, three or four guards rotate shifts to look after to the compound, which includes a sprawling outdoor area. But security is left to CCTV cameras from 10 p.m. to 9 a.m.
Gyeongju city, which is virtually a museum itself, contains around 330 national treasures, only 18 of which are guarded by CCTV cameras at night. One Gyeongju city official said, "We will consider raising the fence around Cheomseongdae to waist-level and assigning night patrols."
A CCTV image of students taking selfies on Cheomseongdae in Gyeongju on Friday