6 wonderful underworlds
The world is not only wonderful in the outdoor but also inside its gut, no matter if it is done by the nature or crafted by humans, a nice and dark world is waiting us if we dare to enter.
The colosseum hypogeum (Rome) is the dark secret place of the colosseum where gladiators prepared, not only physically but also mentally, before their fight until the death.
The puerto princesa underground river (Philippines) is the longest navigable underground river in the world and one of the world's most impressive cave systems. It was declared as UNESCO world heritage site in the category new 7 wonders of nature.
The waitomo caves (New Zealand) is famous for its lovely glowworms that sparkle above your head in the dark and its cathedral, a soaring cavern renowned for its acoustics.
The wieliczka salt mine (Poland) is declared as UNESCO world heritage site and it is worth to discover, particularly its massive mining museum, its concert chamber, its chapels carved from salt, and its sanatorium.
The ainsworth hot springs (Canada) is a natural cave where you will bath into a hot mineral waters raining from its ceiling. You will discover also stalactites and stalagmites and if you get too hot, you can go to its stream-fed cold plunge.
The caves of the thousand buddhas (China), also known as mogao caves, are located in the area of the silk road in the western country where hundreds of caves were dug by monks and decorated with something like 2000 sculptures and paintings.