Concerning Silvia's comment that "cerros are not hills", I disagree.
"cerro" = "hill", not always or necessarily "mountain"
DRAE, cerro: Elevación de tierra aislada y de menor altura que el monte o la montaña.
OED, hill: A natural elevation of the earth's surface rising more or less steeply above the level of the surrounding land. Formerly the general term, including what are now called mountains; after the introduction of the latter word, gradually restricted to heights of less elevation.
But this semantic restriction is not absolute and, in fact, "montaña" and "monte" often correspond to "hill".
Examples:
Cerro San Cristóbal - Wikipedia, the free encyclopedia
24 May 2009 ...
Cerro San Cristóbal is a hill in northern Santiago, Chile. It rises 880 m AMSL and about 300 m above the rest of Santiago; the peak is the ...
en.wikipedia.org/wiki/Cerro_San_Cristóbal
Flickr: skyfenix's Photostream
Hill view. Clouds view by skyfenix.
from a hill in Aguascalientes Mexico --- desde un cerro en Aguascalientes, Mexico. Anyone can see this photo ...
>www.flickr.com/photos/susyinthesky/