In keeping with the Carnaval vibe, tales of its start have the feel of a happy, mid-samba shrug. Where exactly did the festival come from, and how did it get to Rio?
No one's completely sure. Some trace Rio's Carnaval to pagan, ritual celebrations of spring in ancient Rome; others have it imported by Italian Catholics who settled in Brazil and brought their pre-Lenten parties with them [sources: Rio, Brazil Carnival]. Some say homesick Italian aristocrats in the mid-to-late 1800s sparked a trend by throwing parties modeled on Venetian balls [source: Ipanema].
Others look to 1723, when a ritual party called Entrudo made its way from Portugal to Brazil. The purpose of Entrudo was to get everyone in town soaking wet. And throw limes. The latter is said to have gotten the festival cancelled in the 1800s after a woman threw one at the king [source: Ipanema].
Some say masquerade entered the picture under the influence of Rio's wealthy Parisian expatriates. Indeed, Carnival was once a European-style affair; it was only in the early 1900s that Rio's Afro-Brazilian cultural flavors took over, and samba took center stage [source: Rio Carnival].
Far more certain are Carnaval's modern roots. In 1924, a brand-new hotel called the Copacabana Palace held its first ball, a black-tie event attended by Rio's social elite [source: Ipanema]. The Copacabana Magic Ball became an instant, annual fixture in Rio high society, followed in the early '30s by the Official City Gala Ball, which claimed Brazil's president among its first attendees [source: Ipanema].
The Samba School Parade came next, marching through the streets of downtown Rio, and over the following decades, the festival started to look like it does today, with four days of street parties, masquerade balls and parades ending on Fat Tuesday. In 1984, the Sambadrome (or Sambadromo) stadium was built in a shocking 110 days to house the Samba School Parade's tens of thousands of participants and nearly 90,000 spectators [sources: Rio, Rosenfield]. With that, Rio's reign as Carnival central was solidified.
Now, every year, before the start of Lent, the city is overrun by exultant, organized chaos.