Admire the exquisite masonry. The masonry was actually one of the first things Hiram Bingham, Machu Picchu's "discoverer," noticed and admired.
But this is not the sole appeal of Machu Picchu. You can sight-see or learn of the citadel's history from tour guides, while keeping an eye out for ruins still covered by undergrowth and taking photographs of the jaw-dropping scenery. Machu Picchu is not considered among the "seven wonders of the world" without reason. A traveler would be hard-pressed to find a comparable location elsewhere in the world.
Visit the Temple of the Sun, a semi-circular tower on a massive rock slab, reported to have once had precious stones and gold encrusted in its walls. Not too far away sits the clock and altar Intiwatana once used by the Incas in their sacred rite of "tying down" the sun at each year's winter solstice. It is also called the Solar Clock, the Sundial, and the "hitching post of the sun." Its sibling monuments built in other locations by the Inca were demolished by the Spaniards as elements of pagan worship. This remained undamaged until 2001, when authorities allowed a beer commercial to be filmed there, and the crane fell over and chipped the top.
Or perhaps you would prefer to first visit the Temple of the Three Windows, a temple west of the central square with three trapezoidal windows placed so the sun could illuminate the central "Sacred Plaza."
The Sacristy of Machu Picchu, a small cell just behind the Principal Temple, is renowned for its masonry. A visitor can best view the exquisite precision of the Incan stonework there. One stone to the left of the doorjamb has thirty-two distinct angles!
Machu Picchu also has what is called the Royal Sector, which has a still-functioning water canal and chain of fountains. The nearby Royal Tomb has never been found to have human remains, but retains the name from tradition.
Some say the best sight at Machu Picchu is not the ruins at all, but the view of Huayna Picchu (Young Mountain, also spelled Wayna Picchu) beside it. Huayna Picchu towers over the citadel, always viewable, as if standing guard. Platforms that probably once had ritual purposes decorate its peak.
The ruins do have a reasonable admission fee that can be paid in Peruvian soles or U.S. dollars. The entrance fee is $25 US, with students paying half price with an ISIC card. English-speaking tour guides can be arranged, usually costing about $15 to $20 US for a private two-hour tour. Sometimes an individual can join with an established tour group for about $2 or $3 US a person.
To see any the ruins will take some hiking. The trials become harder to hike the higher you go, partially because a number of lesser-used trials have not been restored or maintained. Another factor is the steps, old and sometimes crumbling, and hazardous when wet or muddy. Therefore, you may want to avoid travel to Machu Picchu during the rainy season of November through March.
Hikers can also use trails and take trips of anywhere from a day to a week to reach Machu Picchu through the original gate, encountering monuments and a variety of climates and fauna on the way.