1173
Canonization of Thomas Becket
Alexander III, still at Anagni, formally canonized the murdered archbishop barely two and a half years after his death, one of the fastest canonizations of the Middle Ages. Pilgrims were already flocking to Canterbury; the city's stonemasons could hardly keep up with the shrine construction. Becket's cult spread across Europe with remarkable speed, and within a decade Canterbury had become the richest pilgrimage site in England.
Great Revolt against Henry II
Eleanor of Aquitaine encouraged her sons - Young Henry, Richard, and Geoffrey - to rebel against their father. Louis VII of France and the king of Scotland joined in. Henry crushed them one by one, imprisoned Eleanor for the next sixteen years, and made peace with his sons, who would rebel again.
Leaning Tower of Pisa begun
Construction began on the free-standing bell tower of Pisa cathedral on ground so soft that the building began visibly tilting before the third story was reached. Work stopped for a century while builders debated what to do. It has been tilting and gradually leaning further ever since. Engineers would eventually compensate by building the upper stories slightly taller on one side, giving the tower a subtle banana-curve visible in close photographs.
Valdes of Lyon's conversion
A French merchant named Valdes, on hearing the life of St Alexis sung in a public square, sold his goods, threw coins to the poor, and began preaching. His followers - the Poor of Lyon or Waldensians - would be the most successful dissenting Christian movement of the century. Their insistence on lay preaching and vernacular scripture brought them into direct conflict with a church that reserved both privileges for the ordained clergy.