In 2003 Uruguay issued a set of four stamps commemorating the contributions of four explorers, Christopher Columbus, Juan Díaz de Solis, Sebastian Cabot and Hernando Arias de Saavedra. Each stamp has a map showing the explorer's activities.

     On his fourth voyage to the western hemisphere Columbus, accompanied by his son, Fernando, and his brother, Bartholomew, reached Central America. He was stranded on Jamaica for almost a year.

     In 1516 Juan Díaz de Solis reached and named the Río de la Plata. He sailed up the river to the confluence of the Uruguay and Paraná rivers looking for a route to the Indies. He and most of his small party of nine were killed by the Charrua indians.

     After an unsuccessful attempt to circumnavigate the globe in 1526 Sebastian Cabot sailed up the Río de la Plata looking for an easier route to the Pacific Ocean. He sailed up the Rio Paraná for 160 km and founded the settlement of Sancti Spiritu. After continuing up the Paraná for 800 km he turned back.

     Hernando Arias de Saavedra was the first native-born governor of Asuncion, his birthplace. He explored the borders of the Uruguay and Paraná rivers, and promoted two reforms: the suppression of personal slavery, and the division of the Río de la Plata into two governmental departments, Buenos Ayres and Paraguay.