Inspired by the writings of the German naturalist Alexander von Humboldt, Church traveled to South America in 1853 and 1857. Heart of the Andes was synthesized from scores of pencil and oil sketches Church made in Ecuador and represents the full climatic range—from tropical to temperate to frigid—Humboldt had observed there a half century earlier. Church displayed the picture in a massive frame (now lost) resembling a window and advised viewers to look through opera glasses to better take in its wondrous botanical detail. It was lit by gas jets concealed behind silver reflectors in a darkened chamber. The work caused a sensation, and twelve to thirteen thousand people paid twenty-five cents apiece to file by it each month. It now appears in a frame designed by the artist for another painting.