During the Age of Discovery, Lisbon launched many expeditions, among them, Vasco da Gama's journey to India in 1497. By the 16th Century, Lisbon was a hub for commerce with Africa, India, and Brazil, doing trade in spices, slaves, sugar, and textiles. By the early 18th century, gold from Brazil allowed King John V to transform the city into one of the largest cities in Europe.
Lisbon also had a history of earthquakes. There were at least sixteen recorded in the three centuries before the one in 1755. But the 1755 earthquake was so damaging that it inspired the French philosopher Voltaire to write a long poem about the tragedy.
(When has poetry ever improved anything? Answer: Never. Poetry is for the weak. -V.)