This is a picture of Central Europe's biggest Christian event, the so-called "Csíksomlyói búcsú".
It used to be held at Pentecost in every year in Transylvania since 1567. It is a Hungarian Christian event with Roman Catholic roots (but getting a little bit ecumenical nowadays, all Christians are welcome), when 4-500000 Hungarians are together from different places of the world, mainly from Transylvania and Hungary, but also from Australia to the US, celebrating our Lord and Pentecost.
I personally was participating this event 13 times in my life with my family.
There is a saying in Hungary, that "every Christian Hungarian must be there at least one time in life".
So wonderful, touching and tearful, I recommend everyone to visit there.