Skyscrapers and cutting-edge architecture define the skyline in metropolises like London, Seoul and Shanghai, but these cities still hold pieces of the ancient past.
Some of the remains found in modern cities have become major must-see tourist attractions, while others, despite their impressive age, are mostly ignored by everyone except a handful of history enthusiasts.
Here are nine ancient sites — beyond the obvious examples like the Colosseum and Acropolis — that remain in some of the world's largest, most important cities.
1. Seoul City Wall
The Seoul City Wall, Hanyangdoseong in Korean, dates back to the 1300s. Built to protect the city from invading forces, it originally had sections made of stone and sections made of wood. The wall was used as a fortification until the late 19th century. It was about 11.5 miles long and circled the four mountains that now stand in the heart of the city (Baegaksan, Naksan, Namsan and Inwangsan). Most of the structure was torn down to make way for buildings, roads, train lines and other development projects that have made Seoul one of the world’s most modern cities.
Sections of the wall remain, as do the original gates through which people passed to enter the city. Some of these remnants have been restored, while others have not been altered in the 600-plus years since they were built. The remaining sections have become features in urban parks, and the gates, especially Sungnyemun (South Gate), have been restored and now sit next to glass-dominated skyscrapers.
2. London's Roman Wall
London has a long and colorful history. The seat of power for what was once one of the world’s largest empires has a history that dates back almost two millennia to the time when "Londinium" was controlled by the Roman Empire. Remnants of this era include sections of a crumbling wall that once surrounded the entire city.
The fortification remained important for defensive purposes long after the Romans left. It helped the city repel attacks by Vikings, but it grew obsolete as London expanded. Some of the tallest towers along the wall survived for centuries only to be knocked down by German bombs during World War II. The longest sections that remain intact are on the grounds of the Museum of London and also in the Tower Hill area.
3. Xi'an Wall
Most of China's largest cities once had fortified walls. Almost all of these fortifications have been torn down over the centuries. However, the wall in the city of Xi'an has become an important part of the modern urban landscape. Today, the ancient structure stretches around the core of the city for more than eight miles. Most sections have been repaired over the years, but it's the extreme thickness (more than 50 feet at the base) that has given the wall its longevity.
The walkway at top of the wall is popular with bicyclists and pedestrians because, at 40 feet above the street, it offers a rare respite from the traffic that plagues modern urban China. Rather than tearing down parts of the wall to make room for new roads, this city of 8 million people decided to build new gates in the wall so that cars could pass under it.
4. Templo Mayor
The Templo Mayor is one of the last remnants of Tenochtitlan, the ancient Aztec city that once thrived on the spot where Mexico City now stands. Most of Tenochtitlan was destroyed or covered over during the Spanish colonial period. The Templo Mayor, which was originally built in the 1400s, was not fully excavated until the 1980s, even though archaeologists had a good idea about where it was located long before that.
The Templo is now part of the historic center of Mexico City. It's a few footsteps from the Zocalo, a plaza that can hold nearly 100,000 people. The excavated site is part of a museum. While many of the artifacts were looted after the Aztec Empire fell to the Conquistadors, the few items that remain are now part of the museum's exhibits.
5. Roman Theater in Amman, Jordan
Amman, Jordan is a city of more than 4 million people. It's considered one of the most modern and liberal cities in Middle East. It also has some of the most impressive Roman ruins outside of the Italy. The Roman Theater, constructed during the 2nd century, was completely renovated in the 1950s. Some experts are skeptical of these renovations because some of the materials used were not in keeping with the structure's origins.
Nonetheless, the theater provides one of the most visually interesting contrasts between ancient and modern urban landscapes. Those lucky enough to visit Amman during the summertime may even be able to see a performance in the theater. Events are occasionally scheduled during July and August.
6. Roman Cemetery in Barcelona
Barcelona is known as an energetic city with a youthful vibe. Its skyline is defined by the works of Antoni Gaudi, an architect with a whimsical, modern style. Despite this image, Barcelona is an ancient place. Some historians suggest that the city was first settled by humans more than 7,000 years ago. Recorded history started about 2,000 years ago when the city, then known as Barcino, sprung up around a Roman army base.
Like other Mediterranean cities with such a history, Barcelona has a few remaining walls and columns from Roman times. One of the most impressive ancient sites in the city is a 3rd century cemetery with 70 Roman tombs, which lies inside the modern Plaça Vila de Madrid. The plaza is located adjacent to the always-crowded Las Ramblas pedestrian area.
7. Arènes de Lutèce
Though it's defined by the Eiffel Tower and Arc de Triomphe, Paris has plenty of other interesting sites. Take the Arènes de Lutèce for instance. This Roman arena, which sits in the modern day Latin Quarter in the 5th arrondissement, could seat 15,000 people. It probably hosted gladiatorial bouts and other events. Interestingly, the surrounding neighborhood was known as "les Arènes" for centuries, even after the arena, which had been converted into a cemetery, was filled in.
The stadium was excavated in the 1800s and saved from demolition by a group of Parisians that included famous author Victor Hugo. It was eventually turned into a public square. Though parts of the venue have been replaced, much of the structure is still original.
8. Huaca Huallamarca
Adobe pyramids (or huacas) were built by the Incas. One of the best remaining examples of these ancient structures is Huallamarca. Located in Lima's San Isidro district, which is an upscale financial area, the site was first occupied more than 2,000 years ago by the Hualla people. It was also used by the Incas as a settlement.
Huallamarca was forgotten during the Spanish colonial period, but the site was excavated starting in the 1950s. The main adobe pyramid, with ramps, stairways and platforms, has been unearthed. There is a small museum with artifacts such as dolls, pottery and mummified remains that were found on the site.
9. Dajing Ge Pavilion
Shanghai is the most modern city in China. A financial center on par with New York and London (and exceeding both in terms of population), this metropolis in Eastern China is filled with skyscrapers. Though the Bund is still preserved, there is little remaining of the Old City, which was built between the 11th and 16th centuries.
The Old City Wall was demolished at the beginning of the 20th century to make way for modernization projects. Only one tiny section is preserved in a 19th century structure known as the Dajing Ge Pavilion. Now a museum, the pavilion and renovated wall are dwarfed by surrounding skyscrapers. More extensive ancient fortifications are located in neighboring Suzhou, which has become a large city in its own right.