In 1540 Francisco Vasquez de Coronado marched north from Mexico with 300 Spaniards in search of the Seven Golden Cities of Cibola. Several priests accompanied the expedition, including Juan de Padilla, a Franciscan friar. When the golden cities proved to be only adobe pueblos, the Spaniards continued exploring the Southwest, and Padilla was among those who discovered the Grand Canyon. He later rode with a party of 30 selected horsemen to Quivira in Kansas. Coronado remained for 25 days in the summer of 1541 among the grass-hut villages of the Quiviran Indians, then returned to New Mexico. Padilla went with him, but came back the following year as a missionary. He was later killed by the Indians, becoming the first Christian martyr in what is now the United States, although the exact place of his death is unknown.