A series of tunnels dug under the city - the mines from which the stones for the city's construction were taken. The city is riddled with catacombs - normally the haunt of junkies and down and outs - but outside the city the catacombs operate as a museum.
These tunnels were used by partisans as a base to launch raids against the German and Romanian occupiers. The tunnels are dark and dank and still contain the personal belongings and equipment of the partisans who lived, fought and died there.
The walls are carved with graffiti that is either political or personal (and sentimental) and overall a visit is both a moving as well as interesting experience. It is only possible with a guided tour as the tunnels are confusing and it is easy to get lost.
Above ground is a rather down at heel museum with a few rusty weapons and some interesting, but faded, photographs. Sadly both the tour guide and museum captions are Russian language only.
The only way to get there is by an excursion bus from Odessa city centre. The buses leave at about 1000hrs from outside Odessa Railway Station - little old ladies in the square outside the station sell tickets and can be quite helpful (though generally they only speak Russian). The journey to the catacombs by minibus (included in the ticket price) takes about 40 minutes and the tour itself is about an hour.
Is this your business?