Deep in the heart of the Amazon, the city of Manaus, home to 2 million residents, is the largest city in the rain forest. The city dates back to the end of the 17th century, but it is perhaps best known for the opulence of its late-19th-century gilded age. During the Industrial Revolution, the demand for rubber increased dramatically and the boom led to the so-called rubber barons of Manaus, who built extravagant homes and indulged any whim that money could buy. (The boom ended following the invention of synthetic rubber in 1909.) It was during this period when Manaus became known as the Paris of the Tropics, with the opera house, or Amazon Theater (inaugurated in 1896), helping justify the nickname. After 90 years of neglect, the building was restored beginning in 2001, and once again operas are performed on its stage.