Monte Brasil is the remnants of a tuff volcano (and peninsula) connecting the south coast of Terceira in the central Azores, overlooking the city of Angra do Heroísmo. Monte Brasil is flanked by two bays: the Bay of Angra (named for the city) to its east, and the Bay of Fanal to its west, and was used as a defensive point during the history of Angra, resulting in the construction of various forts and redoubts, including the Fortress of São João Baptista overlooking the city. History The formation of Monte Brasil was the result of various eruptions of the Guilherme Moniz volcano, a large central volcano on the island of Terceira, this difficult to identify owing to subsequent eruptions and lava flows. Although this structure is eroded, there is considerable evidence of its influence, including, specifically: a number of trachyte domes and basaltic eruptive centres around the interior; two Surtseyan cones: Monte Brasil and the Cabras Islets; and several ignimbrite deposits, including the Castelinho, that range to 23000 years of age. An undated human presence on the mount includes artificial cavities located along the hill to provide shelter, but with little vestiges of formal use. Although those on Pico do Zimbreiro are vacant, similar spaces on the roadways to the caldera and Caminho das Belas-donas have bunks along the interior walls. Another grotto on the roadway that skirts the Fort of São Diogo indicates its use as place to collect and store water, including channels, taps and reservoir. Some specialists have speculated that these cavities have been created by ancient cultures, e.g. Phoenicians. These chambers are not suitable for habitation but could be used as simple structures for Phoenician shrines. Such discovery would testify the presence of ancient cultures in Azores long before Portuguese. There are offered also other explanations, e.g. chambers were created in medieval times for the needs of military or agriculture. At the end of the 16th century (around 1590), Monte Brasil was occupied by an estate/farm owned by Manuel do Rego da Silveira and several fortifications, including the Forts of São Benedito and Santo António (towards Angra) and the Fort of São Diogo (in the direction of the Bay of Fanal). The existence of reservoir and staircase, in addition to springs already identified in the 16th century cartography, reinforces the importance of Monte Brasil during this time. From this point forward many of the rock deposits