The question is ambiguous at best. The seven largest Spanish cities, from largest to smallest, are; Madrid, Barcelona, Valencia, Sevilla, Zaragosa, Malaga,and finally Las Palmas de Gra Canaris.
However, the fact that you specified "Seven" Spanish cities makes me wonder if you aren't asking about the Seven Cities of Cibola of legend. If they are what you wish to know about read this link.
http://www.nationalgeographic.com/history/ancient/cibola-cities.html
Africa
The Seven Cities of Cibola
The seven cities of Cibola were called Hawikuh, Halona, Matsaki, Quivira, Kiakima, Cibola, and Tiguex. According to Spanish explorers, these cities were believed to be rich in gold and other resources.
Francisco Vazquez de Coronado was the Spanish nobleman who searched for the Seven Cities of Cibola.
because of they were rich in gold silver and jewels
Coronado.
Francisco Vasquez de Coronado was the Spanish explorer who searched for the Seven Cities of Cibola. They were never found though his units search the American Southwest for years.
The Seven Cities of Cibola are believed to have been located in present-day New Mexico or Arizona. These cities were said to be filled with riches, sparking expeditions in the 16th century by Spanish conquistadors in search of this mythical wealth.
The seven cities of gold, also known as the Seven Cities of Cibola, were rumored to be wealthy cities in the Americas that sparked the interest of Spanish explorers. The cities were never found, but the legends helped drive exploration and colonization in the New World. Ultimately, the cities proved to be a myth, but they played a significant role in shaping early European perceptions of the Americas.
The Seven Cities of Gold refer to the legendary cities purported to have been located in the American Southwest, with their existence fueled by myths and Spanish exploration in the 16th century. These cities were said to be filled with riches, but their actual existence remains a subject of debate and exploration.
expedition to explore Florida and lands to the west
expedition to explore Florida and lands to the west