Boyana Church, Sofia

From the outside it just looks like a little chapel tucked away in a quite suburb of Sofia, but this part of the church was built in the 10th century and when you go inside you are just floored by some amazing 13th century frescoes (which of course they don't let you take pictures of). Just to look at the frescoes for a few minutes was well worth the hassle and a couple very long walks to get there.