Korea again - Incheon - Daegu - Busan - Gwangju - Seoul - 2015 - Page 1 - 46

Very near the top, there were a lot of tunnels such as this. Presumably this was a military look out during the war. Also, note the ice.

Camera Details: SONY, DSC-RX100
Settings: 1/160 at f/5.6, ISO 125, 10 mm
Date: 05 March 2015 Time: 11:47:34