One of the most famous caves "Prohodna" is a karst cave in north central Bulgaria, located in the Iskar Gorge near the village of Karlukovo in Lukovit Municipality. "Prohodna" is 262 metres (860 ft) long, which makes it the longest cave passage in Bulgaria. The cave has two entrances which lie opposite one another, known respectively as the Small Entrance and the Big Entrance. the Big Entrance of "Prohodna" leads to National Cave House Lukovit
Bulgaria, largest South Slavic land in Balkans has a great history where it changed it's shape from kingdoms to empire. This large land of South Slavs has more then one can imagine and we really mean it.