BACKGROUND
The Odessa Catacombs labyrinth approximately 2500 kilmetres under the city and surrounding neighbourhoods. They developed over the last two hundred years, beginning as natural formations and completing with the addition of man-made tunnels. The major part of them are made up of former limestone mines used to build the city's 19thC homes, with the remainder being natural caivities and sewage tunnels. The full extent of the catacombs has not been mapped and is a primary reason a subway system was never built in Odessa.
The first stone mines appeared in the second half of the 19thC with building growth in the city. They were used as a source of cheap construction materials. During World War II, the catacombs served as a hiding place for Soviet partisans and their struggles were detailed in the book The Waves of the Black Sea by Valentin Kataev. Armies were able to house enough food and weaponry to keep them underground for almost six months at a time. In 1961, the Poisk Club was created to explore the history of the partisan movement in the catacombs and it expanded the catographical boundaries of the area.
By the 21stC limestone mines were discontinued in Odessa. Today, the catacombs are a great attraction for "extreme" tourists but you must go in with a guide.
(Some information from Wikipedia - Odessa Catacombs)
(Photo from Wikimedia Commons - Polyschuk Dennis Anatolyevycz)
