Pity St. Walpurga, an English nun from Devon. A night of "devil worship" atop a German mountain is not how she would have wanted to be remembered.

When canonizing Walpurga on May 1, 870, for converting pagan Germans, Pope Adrian II hoped to Christianize a much-loved heathen spring festival. The plan failed, but Walpurga's name stuck.

Today Walpurgisnacht, or May Eve — the night of April 30 to May 1 — is an occasion for revelry and excess in much of Northern Europe, particularly in Germany's Harz mountains, a remote region of dark pine forests, eerie rock formations and blustery peaks.