The couple discovered that they were born within hours of each other on the same day and fell in love quickly. Christo and Jeanne-Claude began working together formally in the 1960s. The couple relocated to New York City, the new art world capital, in 1964. Christo began to make "Store Fronts", wooden facades made to resemble shop windows, which he continued for four years. His largest piece was shown in the 1968 Documenta 4. In the mid-1960s, they also created "Air Packages", inflated and wrapped research balloons. In 1969, at the invite of the museum director Jan van der Marck they wrapped the Chicago Museum of Contemporary Art while it remained open. It was panned by the public and ordered to be undone by the fire department, which went unenforced. With the help of Australian collector John Kaldor, Christo and Jeanne-Claude and 100 volunteers wrapped the coast of Sydney's Little Bay as "Wrapped Coast", the first piece for Kaldor Public Art Projects.