In 1680, Portuguese colonists established Colônia do Sacramento on the northern bank of Río de la Plata, on the opposite coast from Buenos Aires.

The 1750 Treaty of Madrid secured Spanish control over Banda Oriental (present day Uruguay), and settled the boundaries between Spain and Portugal.

[1] In 1776, the new Viceroyalty of the Río de la Plata was established with its capital in Buenos Aires and it included the territory of Banda Oriental.

[2] In October 1998, Uruguayan President, Julio María Sanguinetti, paid a visit to Porto, Portugal to attend the 8th Ibero-American Summit.

[3] In November 2006, both the President of Portugal, Aníbal Cavaco Silva and Prime Minister, José Sócrates, paid a visit to Uruguay to attend the 16th Ibero-American Summit in Montevideo.