We can assure your majesty that it is so beautiful and has such fine buildings that it would even be remarkable in Spain.
—Francisco Pizarro, describing Cuzco in a letter to King Charles V of Spain.
Peru is South America’s third largest country, covering 1,285,215 sq. km., and can be divided into three distinct geographic regions. The best known of these is the central high sierra of the Andes, with its massive peaks, steep canyons, and extraordinary pre Columbian archaeological sites. The Andes are still one of the world’s most unstable mountain ranges, with frequent earthquakes, landslides, and flash floods. Despite such instability, the Andes are also the site of the most fascinating pre-Columbian cities of South America-like the great city of the clouds, Machu Picchu.
The Andes are by no means the only region to visit in Peru. Also of great interest is Peru’s narrow, lowland coastal region, a northern extension of the Atacama Desert. Although the Atacama is generally known as the most arid region on the planet, the climate along Peru’s shores is made cooler and less dry by La Garuùa, a dense fog created by the collision of the frigid waters of the Humboldt Current with the heated sands of the Atacama. Lima, Trujillo, and Chiclayo, three of Peru’s major population centres, are located along this coastal desert.
Peru’s third great region is the dense forest that surrounds the headwaters of the Amazon beneath the eastern slopes of the Andes. This part of the country is so inaccessible that only the most adventurous and intrepid travelers should attempt to penetrate its mysterious emerald depths. In fact, the region’s capital of Iquitos, a city of 400,000, is accessible only by air or by boat up the Amazon.
Peru’s climate varies considerably by region, although January through March tends everywhere to be the wet season. The coastal areas, which are quite hot and humid during those months, are cooled during the rest of the year by La Garuùa. The fog doesn’t penetrate very far inland, however, and the western side of the Andes are very clear, warm, and dry for the greater part of the year. As one moves up into the mountains, night-time temperatures become considerably colder. The eastern slope of the Andes, like the Amazon basin, experiences very heavy rainfall during the wet season, which extends from January all the way through April.
article by: http://www.geographia.com/peru/