There are over 300 kilometres of underground passages underneath Paris, France as underground quarries were made due to the large demand of stone it took to build the city. The catacombs beneath Paris hold nearly 6,000,000 (6 million) human skeletons. During the 18th century, death was quite common and the cemeteries quickly filled up. As such, the city of Paris decided to empty the cemeteries and place the bones underground. The bones were tidied up by making them into walls by stacking skulls and humerus arm bones on top of eachother, making each piece fit in the groove of the next. The collection of bones beneath Paris is essentially the Medieval population of Paris
The Iban people of Sarawak, Malaysia practiced head hunting until the middle of the 20th century. Iban warriors were infamous within the region for decapitating their conquered victims to save the head as a trophy. Heads were strung and hung together at the top of the loadbearing posts of the long houses which the Iban continue to live in during the modern day, housing up to 25 families in a single building. Every month the Iban light small candles or fires below the hanging skulls to keep them warm because if they do not, they believe the spirits of the vanquished enemies will come back to haunt the dreams of the Iban. This practice was used as a right of passage and milestone mark for young Iban men throughout history, with young warriors forced to kill an enemy within the jungle and then bring the head of that enemy back to their home in order to bless it for everyone in the community. It was also common practice for Iban women to carry these skulls up and down the veranda of the longhouse to signify celebration for the bravery of the males of their family