The answer is Machu Picchu.
One of the most important cities of the Inca Empire was Machu Picchu. The reason why it is usually known as the "lost city" is because this city was not discovered by the Spanish when in the 1500s they conquered the Inca territory. Machu picchu is one of the New Seven Wonders of the World nowadays.
European countries were showing their ability to keep up with one another's military might, creating an arms race. No nation readied itself more than Germany.
