In 1851, she set off to Berlin where she was met with an enthusiastic audience. Among them was her childhood hero, Prussian explorer Alexander von Humboldt, whose travels in the Americas inspired a great number of contemporary scientists and naturalists, including Charles Darwin, Henry David Thoreau, John Muir, and Ernst Haeckel. Pfeiffer was also welcomed by German cartographer Carl Ritter who was, at the time, Professor of Geography at the University of Berlin and with whom she would continue to collaborate after her departure. From Hamburg, Pfeiffer set sail to London and met with paleontologist Richard Owen, an outspoken critic of Charles Darwin, geographer Augustus Petermann for his expertise on Africa, and William Bartlett, her traveling companion to Jerusalem.