Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: SEOUL, South Korea (CNN) -- A 69-year-old who was previously convicted of torching a palace has been arrested in connection with a fire that destroyed Namdaemun, South Korea's oldest wooden structure and a national treasure, authorities said on Tuesday. People on Monday look at the debris of the Namdaemun gate in central Seoul after the fire. Similarities between the Sunday night fire and the 2006 blaze led to the investigation of a man identified only as Mr. Chae, said Kim Young-Su, chief of police of the Namdaemun police station. Chae had served time in prison for the palace fire. Police searched the home of Chae's ex-wife and found a can of paint thinner and a pair of leather gloves they believe were used in the fire, Kim said.NEW: "Mr. Chae" was convicted of torching a Korean palace in 2006NEW: Chae has confessed to starting the Namdaemun fire, police chief saysNEW: Easy access, lightly populated area dictated Namdaemun choice, police sayThe more-than-600-year-old Namdaemun was country's oldest wooden structure 
 Question:_ was more than 600 years old and stood at the center of Seoul, having served as a main gate into the capital for centuries.
Output:
Namdaemun