Stories from The House of Habsburg

How were Philip IV of Spain and Mariana of Austria related? — Uncle and niece: Mariana’s mother, Maria Anna of Spain, was Philip IV’s sister. They were also first cousins once removed through Charles II, Archduke of Austria and Maria Anna of Bavaria — Philip’s grandparents and Mariana’s great-grandparents.
Uncles, nieces and cousins: Habsburg marriages within the family — Of the 77 marriages recorded in this Habsburg volume, six joined people who already shared an ancestor: three between an uncle and his niece, two between first cousins, and one between first cousins once removed.
The longest Habsburg line, parent to child — Twenty-three generations, parent to child, from Rudolf I of Germany, born in 1218, to Otto von Habsburg, born in 1912 — 694 years, every birth year in it exact.