Juan de Garay (1528–1583) was a Spanish conquistador. Garay's birthplace is disputed. Some say it was in the Castile city of Junta de Villalba de Losa, while others argue he was born in the area of Orduña (Basque Country). There's no birth certification whatsoever, though Juan De Garay regarded himself as somebody from Biscay (a region from the Basque Country). He served under the Crown of Castille, in the Viceroyalty of Peru. He was governor of Asunción (present day Paraguay) and founded a number of cities in present-day Argentina, many near the Paraná River area, including the second foundation of Buenos Aires, in 1580.
In 1543 he sailed to Peru with his uncle Pedro de Zárate in Viceroy Blasco Núñez Vela's first expedition. In 1561 he took part in the foundation of Santa Cruz de la Sierra. In 1568 he moved to Asunción where he attained political stature. The governor of Asunción sent him in April 1573, with a company of eighty men, on an expedition to the Paraná River, during which he founded the city of Santa Fe de la Vera Cruz. In 1576 he was appointed governor of Asunción. As governor, he attempted to avoid bloodshed by bringing justice and civilization to the natives. To achieve these goals, he founded Indian villages and established local governments.
In 1580, having attained the rank of Capitan General of the Viceroyalty, he re-founded the city on the banks of the Río de la Plata, which was first established by Pedro de Mendoza in 1536 under the name of Nuestra Señora del Buen Ayre, but was later destroyed by the natives. Garay founded Buenos Aires a second time on June 11 in the year 1580. He landed on the riverbank in the location of Plaza de Mayo, calling the city Ciudad de la Trinidad and its port Santa Maria de Buenos Ayres. Buenos Aires would become the main city in the Paraná basin and its most important port.