One of the new 7 Wonders of the World and built in 1450-1460. It is worth all the effort it takes to get there. Planes, trains and buses add to the experience. Note * Since we have been there (pre 2010) the Urubamba River reeked havoc around Agua Caliente, but the wonderful Peruvians we met there were a hardy bunch and hopefully visits to Machu Picchu are back to normal.