Though bus and train connections are available, the fastest way to the city is by plane, which takes only an hour from Lima. Air connections are also available from the Peruvian cities of Arequipa and Puerto Maldonado and La Paz, Bolivia.
Americans must have a valid passport and proof of return or onward travel. You may stay for up to 90 days. However, immigration officials determine your actual period of stay when you enter the country.
Bring plenty of water and pace yourself since you won't be accustomed to the 2-mile high atmosphere. Start your walking tour in the Main Plaza, where Incan walls and temples, as well as Spanish churches, are a short distance away. See Resources for an itinerary.
The Incan fortress of Sacsayhuaman is a steep 30 minutes from the plaza. It could once house 10,000 men and features the ancient stone walls that fit precisely without mortar.
The fabled city of Machu Picchu is three hours away by train or 30 minutes by helicopter. You can also make the four-day trek on the Inca Trail, which is best done with an organized tour that handles camping, porterage and fees. See Resources for a link.