 Fonseca grew up in the West Village of Manhattan, New York City, where his father had his sculpture studio.He lived for five years in Barcelona, Spain, where he studied under , whose father had taught Gonzalo Fonseca in Uruguay in the 1940s.After this he spent some time in Uruguay, moved for several years to Pietrasanta, close to the marble quarries of Carrara in north-western Tuscany, Italy, and then lived and painted in Paris.