Machu Picchu is not actually the name of the citadel but the mountain behind the famous citadel. Same as the Inca people actually refers to the king of the Quechua people and not the entire people.
Machu Picchu is a 15th-century Inca citadel located in the Eastern Cordillera of southern Peru on a 2,430-meter (7,970 ft) mountain ridge. Often referred to as the “Lost City of the Incas”, it is the most familiar icon of the Inca Empire. It is located above the Sacred Valley, which is 80 kilometers (50 mi) northwest of Cusco. The Urubamba River flows past it, cutting through the Cordillera and creating a canyon with a tropical mountain climate.
The Quechua Civilization had no written language and no European visited the site until the 19th century, so far as is known, so there are no written records of the site while it was in use. Machu Picchu was built in the classical Inca style, with polished dry-stone walls. Its three primary structures are the Intihuatana, the Temple of the Sun, and the Room of the Three Windows. Most recent archaeologists believe that Machu Picchu was constructed as an estate for the Quechua emperor Pachacuti (1438–1472). The Quechuas built the estate around 1450 but abandoned it a century later, at the time of the Spanish conquest. The site was probably called Huayna Picchu by the Inca people themselves, as it exists on the smaller peak of the same name.