Located in a remote community near the Isthmus of Tehuantepec, the organ of Santiago Guevea de Humboldt is unique in the group of extant Oaxaca organs. Its keyboard is positioned at the back of the organ and is in almost perfect condition due to its hidden location. The pitch is a= 370 Hz, a half tone below 392 Hz and a tone and a half below modern pitch 440 Hz; it has the lowest pitch of any Oaxaca organ. It is a mid-18th century 4´ table instrument, but unlike the others in its category, it has no doors or accessory stops. The case and mechanics are complete, and only the carved decoration from the crest of the central tower is missing. Angel musicians adorn the sides of the case, on the left playing a cornet and on the right a bassoon, while rustic faces on the façade pipes merge into multi-colored swirling designs. The first pipe of the three main ranks (flautado, bardon, octava) and the first pallet of the windchest are incribed with Maltese crosses. The date of the organ was discovered on a paper label on the façade. The IOHIO photographed an extensive collection of 19th-century manuscripts of religious band and choral music, which had been piled on top of the bellows for years, and delivered a digital copy to the local authorities.