The Wieliczka Salt Mine, located near Krakow, Poland, has been exploited since the 13th century and was listed in the United Nations World Heritage List in 1978. The salt mine has 9 floors underground, 245 kilometers of tunnels, and 2391 caverns for business, meetings, and praying. It is one of the oldest and largest salt mines in Europe. As a national historical site of Poland, millions of people from all over the world travel here every year. Today, as we walk into this underground maze from the perspective of a wood lover, the mystery of the salt mine lies not only in the magnificent world of ancient underground spectacle and salt, but also the ubiquitous wood shelters which lead people to pursue the salt miners' steps and feel their work and life, diligence and wisdom.