Gemelli Careri realized that he could finance his trip by carefully purchasing goods at each stage that would have enhanced value at the next stage: at Bandar-Abbas on the Persian Gulf, he asserts, the traveler should pick up "dates, wine, spirits, and all the fruits of Persia, which one carries to India either dried or pickled in vinegar, on which one makes a good profit".
Gemelli Careri started his world trip in 1693, with a visit to Egypt, Constantinople, and the Holy Land. At the time, this Middle Eastern route was already becoming a standard ingredient of any excursion into foreign lands, a hike that was almost not worth writing home about. However, from there the Italian 'tourist' would take less traveled paths. After crossing Armenia and Persia, he visited Southern India and entered China, where the Jesuit missionaries assumed that such an unusual Italian visitor could be a spy working for the pope. This fortuitous misunderstanding opened for Gemelli many of the most tightly closed doors of the country. He got to visit the emperor at Beijing, attended the Lantern Festival celebrations and toured the Great Wall.
"Most of the structure, as has been said, is of brick, so well built that it does not only last but looks new after several ages. It is above 1800 years since the Emperor Xi-hoam-ti caused it to be built against the incursions of the Tartars. This was one of the greatest, and most extravagant works that ever was undertaken. In prudence the Chinese should have secured the most dangerous passes: But what I thought most ridiculous was to see the wall run up to the top of a vast high and steep mountain, where the Birds would hardly build much less the Tartar horses climb... And if they conceited those people could make their way climbing the clefts and rocks it was certainly a great folly to believe their Rage could be stopped by so low a wall."
From Macau, Gemelli Careri sailed to the Philippines, where he stayed two months while waiting for the departure of a Manila galleon, for which he carried quicksilver, for a 300% profit in Mexico. In the meantime, as Gemelli described it in his journal, the half-year-long transoceanic trip to Acapulco was a nightmare plagued with bad food, epidemic outbursts, and the occasional storm. In Mexico, he became friends with Mexican creole patriot and savant Don Carlos de Sigüenza y Góngora, who took the Italian traveler to the great ruins of Teotihuacan. Sigüenza spoke with Gemelli about his theories of the ancient Mexicans and entrusted him with information about the Mexican calendar, which had appeared in Gemelli's account. As well as having visited the pyramids at Teotihuacan, he also visited several mining towns. After leaving Mexico city he visited the city of Puebla de Los Angeles and several towns as he traveled to the port city of Veracruz, where he joined a Spanish fleet headed toward Cuba. After nearly five years of wandering around the world, Gemelli was finally on his way back to Europe when he joined the Spanish treasure fleet in Cuba.