São Paulo is the largest city in Brazil, with a city population of about 11 million and almost 20 million in its metropolitan region. It is the capital of the Southeastern state of São Paulo, and also a beehive of activity that offers a jovial nightlife and an intense cultural experience. São Paulo is one of the richest cities in the southern hemisphere, though inequality between the classes typically observed in Brazil is blatant. Historically attractive to immigrants as well as (somewhat later) Brazilians from other states, it's one of the most diverse cities in the world.
São Paulo, or Sampa as it is also often called, is also probably one of the most underrated cities tourism-wise, often overshadowed by other places in the Brazilian sun & beach circuit such as Rio de Janeiro and Salvador. It is in fact a great city to explore, with its own idiosyncrasies, the exquisite way of living of its inhabitants, not to mention the world-class restaurants and diverse regional and international cuisine available to all tastes. If there is a major attraction to this city, it is the excellent quality of its restaurants and the variety of cultural activities on display.
Just south of the city, lies the Parque Estadual Serra do Mar (part of the Atlantic Forest South-East Reserves, a UNESCO World Heritage Site), a mountain range covered by exhuberant rainforest that faces the coast and provides various ecotourism options.