The largest library in Latin America, and the eighth largest in the world, Rio ’s Biblioteca Nacional (Av. Rio Branco 219, Centro, tel. 21/3095-3879 or 3095-3811, www.bn.br , 9 a.m.–8 p.m. Mon.–Fri., 9 a.m.–3 p.m. Sat.) boasts some 13 million tomes—the first of which were brought to Brazil  by Dom João VI in 1808. Completed in 1910, the building is an eclectic fusion of neoclassical and art nouveau styles.
You don’t have to be a serious bibliophile to opt for a guided tour (R$2) of the grandiose interior (tours begin at 11 a.m., 1 p.m., and 3 p.m. on weekdays).