By Maggie Sullivan

It’s said that those who can’t remember the past are doomed to repeat it. But sometimes this isn’t a bad thing. Herewith, our 10 favorite cases in point.

1. Potala Palace, Lhasa, Tibet.
Looming at an altitude of 12,000 feet, the Potala Palace presides over Lhasa as a spiritual symbol of the Buddhist faith. Tibetans arrive daily from pilgrimages to the majestic 13-story palace, built in three stages, the first by Emperor Songsten Gampo in 637 A.D. The white and crimson palace is virtually untouched despite the troubles that have plagued Tibet, leaving the gilded tombs and living quarters of past Dalai Lamas and ancient murals, sculptures, and statues for visitors to admire.

2. Pyramids and Sphinx, Giza, Egypt.
In a country synonymous with antiquities, Giza is an obvious choice for those interested in archeology. Even though the area has long been overrun by tourists and souvenir hawkers, it will forever remain high on our list of favorites for its astonishing size and nostalgic pull at any explorer’s heart. Little known fact: The regal Sphinx that stares out into the limitless desert became a casualty of war in the 18th century when its nose was lost to the Ottomans who used it for target practice.

3. Newgrange, Boyne Valley, Ireland.
Newgrange predates both the pyramids and Stonehenge, but it lacks the celebrity of either. The ornamentation and alignment of the passage tomb suggest the pre-Celtic inhabitants of the valley were sun worshippers. Legend even posits that it’s the grave of Aengus, the Irish god of love. Restored to archaeologists’ best guess at its appearance in 3,200 B.C., the face of white quartz and granite and the surrounding circle of engraved standing stones rise dramatically from surrounding countryside.

4. Angkor, Cambodia.
The celebrated Angkor Wat is just one temple in a 100-monument complex covering more than 240 square miles that was once the capital of a mighty Khmer Empire. The region also possesses an ingenious system of irrigation canals that were essential for the effective cultivation of rice, the source of the empire’s economic power. The temples of Angkor exemplify the balance in spirituality, architecture, economy, agriculture, and art valued by the Khmer. Artisans also created delicate sculpture and bas reliefs--best viewed from left to right--that represent Indian epics, sacred texts, and the military history of the time.

5. Petra, Wadi Musa Canyon, Jordan.
An ancient caravan city carved from red sandstone cliffs some 5,000 years ago, Petra is not to be missed. Entrance--either by foot or horseback--is through the narrow Siq Pass, which leads to awe-inspiring temples, tombs, and palaces. The famous Khazneh (Treasury) is the first monument you see as you emerge from the canyon. The Royal Tombs are close by, but it’s a long hike to the monastery and High Palace of Sacrifice. An even more strenuous route takes you to the top of Umm Al Biyara, where the views over Petra are mind-boggling. Just remember to take plenty of water; there are no rest stops along the way.

6. Machu Picchu, Peru.
The Inca Empire lasted just 300 years, but the great city it built, unearthed in 1911, should have considerably more staying power. No one knows why or how the complex came to be--the structures involved great feats of architectural ingenuity--or why it was eventually abandoned. But the location must have appealed to the Inca reverence of all things natural. Accessible by train or on foot via the Inca Trail, Machu Picchu is well-managed and well-preserved. Alas, it also can be filled with swarms of tourists. Thankfully, though, few of them seem to rise early enough for the pièce de résistance: the serene, otherworldly peace of watching the sun rise over the ruins.

7. Tikal National Park, Guatemala.
In the heart of this jungle lies one of the major sites of Mayan civilization, inhabited from the 6th century B.C. to the 10th century A.D. Surrounded by dense, broad-leaved forests with more than 300 species of trees that are useful to man, such as cedar, West Indian mahogany, and ceiba (a tree sacred to the Maya), this ancient ceremonial center contains magnificent temples, palaces, and ramps leading to public squares, which you can explore to the cacophonous calls of the many macaws who stand guard.

8. Tombouctou, Mali.
Though its name is synonymous with the back of beyond, at its height Timbuktu--as it’s more commonly known in the West--was a powerful and wealthy center of Islamic learning and culture and the heart of West Africa’s gold and salt trades. So it’s no wonder that this mysterious city became a Holy Grail for European explorers seeking fame and fortune. But it wasn’t until 1828 that Frenchman René Cailleé reached the caravan city and returned to tell the tale. By then, however, the city was only a shadow of its former self. Nevertheless, you get a pretty good sense of the city it was as you wander the wide, sand-clogged boulevards viewing the city’s ingenious adobe architecture. Planks jutting out from the walls at regular intervals create a handy ladder for post-rain repairs.

9. Acropolis, Athens, Greece.
Habitation of the Acropolis appears to date back to the Neolithic period, but the buildings that make it so identifiable were initiated under the rule of Pericles between 447 and 432 B.C. The Parthenon, probably the most characteristic construction of ancient Greece, was dedicated to Athena, patron goddess of the city. It has served as a temple, Byzantine church, Latin church, Muslim mosque, and--before it was nearly destroyed by a Venetian cannon--Turkish gunpowder storehouse. Alongside the Parthenon, which is a fine example of Doric architecture, sit models of the later Ionic style: the Temple of Athena Nike along with the Erechtheion, noted for its porch of six larger-than-life maidens.

10. Cliff Palace, Mesa Verde National Park, Colorado, U.S.A.
Although ruins are scattered throughout the cliff overhangs and canyons, the Cliff Palace is the largest and most recognizable of the Mesa Verde pueblos. It’s not clear whether these pueblos were constructed beneath these overhangs as a defense against enemies or the weather, but they were almost certainly deserted after a long and devastating drought. The 150-room complex, which includes towers, courtyards, and ceremonial kivas, remained a veritable ghost town for more than 500 years, until two farmers in search of lost cattle stumbled upon them. Their loss, our gain.

Maggie Sullivan is an assistant editor at iExplore.