In 1949, shortly after meeting artist Mary Lockspeiser, Frank traveled to Europe. He stopped in Switzerland to visit his parents before going on to Paris, where he would be based until the end of the year. There, he created Mary's Book, a unique book of 74 photographs dedicated to Mary. Designed as a romantic love poem to the woman he would marry the following year, the book features an intricate layout and inscriptions in both French and English. During this trip, he also traveled and photographed in Spain and Italy.
After the birth of their son, Pablo, in February 1951, Robert and Mary returned to Europe for a two-year sojourn from 1951 to 1953. This time, they stayed in Paris, London, Zurich, Wales, and Spain. As in Peru and lower Manhattan, Frank's photographs focused on elements that expressed the character of each place he visited. In Valencia he photographed bullfights and animals; in London he shot bankers in top hats; and in Paris he recorded flowers, chairs, and street vendors. Before returning to the United States in March 1953, Frank undertook a more intimate exploration of the life of miners in Caerau, Wales, again on the advice of Edward Steichen. There, Frank lived with miner Ben James and his family for several days, photographing James as he worked, ate, even washed in a small basin in his home. Back in New York, Mary gave birth to the couple's daughter, Andrea, in April of 1954.