Wilhelm und Alexander von Humboldt at the German History Museum

Alexander von Humboldt was the first to depict the regions he visited in 3D — or to have them depicted this way. They include the Andes as seen in this picture by Aimé Bonpland. This method revealed different layers of earth and vegetation zones. During his expedition to the Andes, Humboldt climbed the summit of the Chimborazo volcano and described the experience of altitude sickness.

On his journey through today's Venezuela, Peru, Mexico and Ecuador, Humboldt opted not to take a draftsman long. Instead, he sketched his impressions himself — presumably also this llama in an illustration from 1802. Using line drawings, he proceeded quickly and precisely. During his trip to the New World, he completed around 450 illustrations of plants, animals and landscapes.

The original 13-foot-high sun stone that Alexander von Humboldt encountered in Mexico City depicts the sun god Tonatiuh with tongue extended. Humboldt identified it as an Aztec calendar stone. For him, this was the occasion to delve into old calendar and zodiac systems in America, Asia, Africa and Europe.

Alexander von Humboldt spent five months of research in Cuba, which by then had been in Spanish hands for 250 years. "Without a doubt, slavery is the greatest of all evils," he wrote. Cuba today still fondly recalls the researcher from Germany. Numerous monuments, streets and a national park in Cuba are named after the German scientist.

In his notes, Alexander von Humboldt listed 75 instruments he used on his expedition to the Americas. They include instruments for determining position and time, for navigation or for analyzing the air. This protractor was developed by an instrument maker named Jesse Ramsden. Humboldt's tools were among the most modern measuring instruments of the time.

Alexander von Humboldt wrote and drew at this desk for 30 years. Made of birch, it has two large drawers and a removable drawing board. This is where he penned the second part of the legendary Kosmos lecture series and many other texts. Humboldt purchased the desk immediately after his move from Paris to Berlin, where he died on May 6, 1859.

Alexander is considered to be the Humboldt brother who was more eager to travel, but Wilhelm also regularly visited faraway lands. In 1799 he traveled to the Pyrenees as part of a group that took a scientific interest in the mountains. The above oil painting is by Alexandre Louis Robert Millin du Perreux (1802), whom Wilhelm met on the trip.