This is the Rason Special Economic Zone, one of North Korea's most ambitious attempts at economic reform.
But since the execution of Jang Song-thaek, the once-powerful uncle of North Korean leader Kim Jong-un, the once-dynamic district has become a ghost town.
Jang had been in charge of the development project, working closely with Beijng to attract Chinese investment.
Sources say that several North Korean officials who worked with Jang on the project have also been purged as the North continues to remove Jang's close aides from the ranks of the ruling elite.
South Korea's unification ministry said that is a highly likely scenario, as North Korea is reshuffling party officials following Jang's execution, and those involved in the Rason project will likely not be an exception.
The ministry could not, however, provide details on the issue.
At the time of Jang's execution, the North had accused him of selling land in the Rason economic zone to China at giveaway prices.
"Jang had no scruples about committing such a treacherous act last May as selling land in the Rason economic zone to a foreign country for a period of five decades under the pretext of debt."
Sources say the officials who took part in negotiations with China on the land sale were the first on the list to be questioned.
Hwang Sung-hee, Arirang News.