Hostels Can A 17 Year-old Stay In Youth Hostels In Eurpoe Without A Parent Or Guardian?

Can a 17 year-old stay in youth hostels in Eurpoe without a parent or guardian? - hostels

My son graduated from high school and some of his friends were backpacking through Europe. Are 18, but only 17 and not later than 18 August - after his return. He could stay in the hostels without a guardian? Any other question has not been made available?

Thank you!