Cariocas joke that the best thing about Niterói is the view—on a clear day you can see Rio de Janeiro with the Corcovado and Sugarloaf across the bay. But Niterói has the last laugh, as the city is ranked as having the highest quality of life in the state.
Catch a ferry from Rio's Praça 15 de Novembro and cross the bay in 20 minutes. From the Praça Araribóia or at the Terminal Hidroviário de Charitas, walk along the esplanade to the Forte de Gragoatá and then walk to Museu de Arte Contemporânea, whose Oscar Niemeyer–designed building and views of Rio are more impressive than the art. Icaraí beach is a smaller, less touristy version of Copacabana. If you have time, enjoy a beer on the beach and watch the sunset over Rio and the Corcovado. Don't plan to spend more than one afternoon in Niterói. Instead head up the Blue Coast to Búzios or Cabo Frio. The tourist office is located next to the ferry terminal.