Premise: The square (also called by its former name Terreiro do Paao), wholly wiped out by the great earthquake of 1755, has seen its share of watershed political King Carlos and his son were felled by an assassin's bullets there in 1908, and it was the site of one of the first uprisings of the Carnation Revolution of 1974.

Hypothesis: There was an earthquake in the mid 18th century that destroyed a square.
Relation: entailment