• Colonial Lima: The old center of Lima Centro preserves a wealth of fine colonial-era buildings that have survived fires, earthquakes, and decades of inattention. Churches include San Pedro (the best-preserved example of early colonial religious architecture in the city), La Merced, and San Agustín. Equally interesting are the historic quarter's few remaining casas coloniales, such as Casa Riva-Agüero, Casa Aliaga, and Casa de Osambela Oquendo. Though the capital's unruliness makes appreciating its colonial core a bit daunting, it's worth the effort.
  • Cusco's Inca Masonry: Everywhere in Cusco's old center are stunning Inca walls, made of giant granite blocks so amazingly carved that they fit together without mortar, like jigsaw puzzle pieces. For the most part, the colonial architecture has not stood up nearly as well as the Incas' bold structures, which are virtually earthquake proof. The best examples are the curved stones at the Sun Temple, Qoricancha; along Hatunrumiyoc, an alleyway lined with polygonal stones and featuring a 12-angled stone; and another pedestrian-only alleyway, Inca Roca, which has a series of stones that forms the shape of a puma.
  • The Mystery of Moray: A peculiar Inca site with a mystical reputation, Moray isn't the Inca version of the Nasca Lines, although it sure looks like it could be. A series of inscrutable ringed terraces sculpted in the earth, the deep-set bowls formed an experimental agricultural center to test new crops and conditions. The different levels produce microclimates, with remarkable differences in temperature from top to bottom.
  • Ollantaytambo's Old Town: Though "Ollanta" is best known for its Inca ruins perched on an outcrop, equally spectacular is the grid of perfectly constructed canchas, or city blocks, that reveal the Incas as masterful urban planners as well as stonemasons. The 15th-century canchas, amazingly preserved, each had a single entrance opening onto a main courtyard. Rippling alongside the lovely stone streets, canals carry water down from the mountains.
  • Machu Picchu's Temple of the Sun: Even as ruins, Machu Picchu rises to the stature of great architecture. Brilliant elements of design and stonemasonry can be found around every corner, but perhaps the greatest example of architectural prowess is the Temple of the Sun. A tapered tower, it has the finest stonework in Machu Picchu. A perfectly positioned window allows the sun's rays to come streaming through at dawn on the South American winter solstice in June, illuminating the stone at the center of the temple. A cave below the temple, carved out of the rock, has a beautifully sculpted altar and series of niches that create mesmerizing morning shadows.
  • Colonial Arequipa: The colonial core of Arequipa, Peru's second city, is the most graceful and harmonious in the country. Most of its elegant mansions and churches are carved from sillar, or white volcanic stone. The Plaza de Armas is one of the prettiest main squares in Peru, even though the cathedral was recently damaged by a major earthquake. Other colonial churches of note are La Compañía, San Francisco, San Agustín, and the Monasterio de la Recoleta. Arequipa also has some of Peru's finest colonial seigniorial homes, which feature beautiful courtyards, elaborately carved stone facades, and period furnishings. Don't miss Casa del Moral, Casa Ricketts, and Casa Arróspide.
  • The River Architecture of Iquitos: A humid Amazon river city, Iquitos might not be a place you'd expect to find distinguished architecture, but the rubber barons who made fortunes in the 19th century lined the Malecón Tarapacá riverfront with handsome mansions covered in colorful Portuguese glazed tiles, or azulejos. The best are Casa Hernández, Casa Cohen, Casa Morey, and the Logia Unión Amazónica. Also check out the Casa de Fierro, designed by Gustave Eiffel and entirely constructed of iron in Paris and shipped to Peru, or the wild wooden houses on stilts in the often-flooded shantytown district of Belén.
  • Trujillo's Casas Antiguas: The colorful pastel facades and unique iron window grilles of Trujillo's colonial- and Republican-era houses represent one of Peru's finest architectural ensembles. Several have splendid interior courtyards and mudéjar-style (Moorish-Christian) details. Fine homes grace the lovely Plaza de Armas and the streets that radiate out from it. Among those outfitted with historic furnishings and open to the public are Palacio Iturregui, Casa Urquiaga (where Simón Bolívar once lived), Casa de la Emancipación, and Casa Orbegoso.
  • Cumbe Mayo's Aqueduct: This weird and wonderful spot near Cajamarca draws visitors for its strange rock formations that mimic a stone forest. But the structure that was engineered by man, a pre-Inca aqueduct constructed around 1000 B.C., is most extraordinary. The 8km (5-mile) canal is carved from volcanic stone in perfect lines to collect and redirect water on its way to the Pacific Ocean. Right angles slow the flow of water and ease the effects of erosion. The aqueduct is likely the oldest manmade structure in South America.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.