Terceira (tɨɾˈsɐjɾɐ) is a volcanic island in the Azores archipelago, in the middle of the North Atlantic Ocean. It is one of the larger islands of the archipelago, with a population of 53,311 inhabitants in an area of approximately 396.75 km2. It is the location of the Azores' oldest city, Angra do Heroísmo, the historical capital of the archipelago and UNESCO World Heritage Site; the seat of the judicial system (Supreme Court); and the main Air Force base, Base Aérea no 4 at Lajes, with a United States Air Force detachment.
The island has two main sea ports, one at Angra do Heroísmo and the other at Praia da Vitória, and a commercial airport integrated with the flight operations at Base Aérea no 4. The Portuguese bullfight is popular on the island, coming in two variations: the traditional equestrian bullfight (in the ring) and the popular "touradas à corda" that occur in the streets.
Historically, there has been uncertainty in the date and the discoverer associated with the islands of the Azores. Nautical charts before the "official" discovery identified islands in the Atlantic Ocean as far back as 1325, when a chart by Angelino Dalorto identified "Bracile" west of Ireland, and later one by Angelino Dulcert which identifies the Canaries, and Madeira, along with mysterious islands denominated as "Capraria" (which some historians suggest were São Miguel and Santa Maria). Legends also persisted of Atlantis, Sete Cidades (Kingdoms of the Seven Cities), the Terras of São Brandão, the Ilhas Aofortunadas (The Fortunate Islands), the Ilha da Brasil (the Island of Brasil), Antília, the Ilhas Azuis (Blue Islands), and the Terra dos Bacalhaus (Land of Codfish), and charts appeared between 1351 and 1439 of several groupings of islands with various names. The first association between the modern island of Terceira and these stories, was that of the island of Brasil; it first appears as Insula de Brasil in the Venetian map of Andrea Bianco (1436), attached to one of the larger islands of a group of islands in the Atlantic
In 1439, the first official discovery document appeared, attributing the discovery of the Formigas to Gonçalo Velho Cabral.