Located in Urca, at the foot of Pão de Açúcar, Fortaleza de São João is a landmark of the founding of the city of Rio de Janeiro and a key piece in the defense of Guanabara Bay. Its formation dates back to the redoubt of São João, which received reinforcements from other small fortifications in the following years, such as the redoubts of São Teodósio (1572), São José (1578), and São Diogo (1618). The four fortifications were later united into a larger fortress, improved and expanded, used to confront the Dutch, French, and pirates. In 1855, Emperor D. Pedro II authorized the installation of a military school in the fortress, which in the 20th century received new schools and a museum, being listed in 1938. Currently, part of its facilities is open to tourism, and the fortress is part of the UNESCO World Heritage candidate ensemble.