Borja is a town and municipality in the province of Zaragoza, community of Aragon, northeastern Spain. As of 2014, its population was 4,931.
The municipality borders with Ablitas (in Navarre) Agón, Ainzón, Alberite de San Juan, Albeta, Ambel, Bulbuente, El Buste, Fréscano, Magallón, Maleján, Mallén, Tabuenca, Tarazona, and Vera de Moncayo. It is the administrative seat of the comarca of Campo de Borja.
The town's origins date back to the fifth century BC, because this is when a Celtiberian settlement known as Bursau or Bursao had existed near the current ruins of the castle. After the Roman conquest (first century BC) also the slopes of the hill were populated, though the town started to expand significantly only after the Muslim conquest in the eighth century AD.[citation needed]
In the twelfth century it was conquered by the Christians from the north, and in the fifteenth/16th centuries it was converted into a military fortress against the Castillan invasions, but at the same time received much of its historical architectural heritage, with numerous churches and palaces. It received the title of "city" by King Alfonso V of Aragon in 1438. During the reign of the Catholic Monarchs, the Jews, forming an important part of the Borjan community, were expelled.
The House of Borgia, which rose to prominence during the Italian Renaissance, originated in Borja and their name was a variant of the town's name. However, since at the time when they lived in Borja they were not yet especially prominent, their earlier history remains largely unknown.
Borja existed through a period of recession and plagues in the seventeenth and eighteenth centuries. It recovered economically starting from the nineteenth century, when a railway connecting the city to Cortes, in Navarre, was inaugurated. In the twentieth century agriculture, traditionally the mainstay of Borja's economy, started to lose its importance, and, without a consistent industrial base, the city lost economical and political importance in the area: much of the population therefore emigrated to other more developed areas. The industrial sector is intended to be boosted by businesses being attracted to the ongoing development "Polígono Industrial Barbalanca", the Barbalanca Industrial Estate.