1. Tokyo began life as a village known as Edo.

The city that would become one of the world’s largest metropolises started out as a small fishing village, first settled around 3,000 B.C. Known as Edo, or “estuary” it was first fortified in the 12th century and became home to Edo Castle (now the site of the Imperial Palace) in the 1450s. Edo’s influence and growing importance in Japanese society was due to its role as the base of power for the Tokugawa shogunate, which ruled the country for more than 250 years until its overthrow in 1868. During this era, known as the Edo period, the city underwent unprecedented cultural and economic growth and by the 1720s the population had boomed to more than 1.1 million, making it one of the largest cities in the world. The city’s name was formally changed to Tokyo, meaning eastern capital, in 1868, when the nearly 700-year shogunate period came to an end, and the new emperor, Meiji, moved his residence there. Although Tokyo has remained the de facto capital ever since, there are no rules on the books making it Japan’s “official” capital, leaving some in the former imperial city of Kyoto to insist that it is the rightful owner of the title.

2. A massive earthquake destroyed nearly half of Tokyo in 1923.

Just before noon on September 1, 1923, a massive earthquake, measuring between 7.9 and 8.4 on the Richter scale, erupted just 30 miles south of Tokyo, unleashing a massive burst of energy that wreaked unprecedented damage on both Tokyo and the nearby city of Yokohama, Japan’s largest port. The Great Kanto Earthquake destroyed more than 45 percent of Tokyo and killed more than 140,000, making it the deadliest natural disaster in Japanese history and the country’s second most powerful earthquake, surpassed only by the 9.0 magnitude Tohoku earthquake that triggered a massive tsunami in 2011. One of the largest losses of life occurred near the Sumida River, as more than 44,000 Tokyo residents took shelter there from encroaching flames. Late that afternoon, a 300-foot-tall ball of fire engulfed the area, killing all but 300 of those gathered. As authorities–hampered by the near total destruction of the city’s water mains–struggled to contain the fires, rumors spread throughout the city of widespread looting and vandalism by Korean immigrants, angered by Japan’s 1910 annexation of Korea. The rumors were unfounded, but that did little to stop a massive wave of reprisal killings—upwards of 5,000 Koreans were massacred in the days following the earthquake.

3. The Allied bombing of Tokyo was just as destructive as that of Hiroshima and Nagasaki.

World War II-era bombing of Japan began just months after the surprise attack at Pearl Harbor, when aviator James Doolittle led his famed raid of 16 B-25 bombers on targets in Tokyo and Yokohama. Aerial attacks intensified in late 1944 following the Allied capture of Pacific islands that put them (and the new, highly advanced B-29 bomber) in striking distance of Tokyo. In the following months, the Allies began a devastating series of nighttime firebombing raids, culminating in Operation Meetinghouse, when more than 2,000 tons of incendiary bombs were dropped over Tokyo in just 48 hours, destroying 16 square miles around the city and killing between 80,000 and 130,000. It remains the single most destructive bombing raid in history.

4. Tokyo has the world’s busiest metro system.

First opened in 1927 and greatly expanded in preparation for the 1963 Summer Olympics, Tokyo’s mass transit system, only part of which runs underground, is the busiest in the world, ferrying more than 8.7 million commuters a day–and more than 3.2 billion annually–along its 200 miles of tracks. Congestion in the system is so great that metro officials have long employed a fleet of oshiya, or “pushers,” whose job it is to safely cram as many people as possible into overcrowded subway cars. In March 1995, Tokyo’s subway system was the target of domestic terrorism attack when members of the Aum Shinri Kyo doomsday cult carried out a sarin gas attack in several stations, killing 13 people and injuring more than 1,000.

5. Japan is home to the oldest monarchy in the world.

Dating from approximately 660 B.C., the Imperial House of Japan has seen 125 monarchs placed on what is often known as the Chrysanthemum Throne, making it the longest lasting continuous monarchy in the world. With just a few exceptions (including a few early 19th century reigning empresses) the throne has been held exclusively by men. In 2005, a judicial panel recommended doing away with laws restricting the monarchy to males, but no changes have been made official. The reigning emperor, Akihito, assumed the throne in 1989. Unlike nearly all of his imperial predecessors, Akihito never served in the Japanese military, instead attending the prestigious Gakushuin University, where his classmates included musician and artist Yoko Ono.

6. Tokyo is home to more people than any other metropolitan area.

Today, the larger metropolitan Tokyo area is home to more than 35 million people, with more than 13 million residing in the city center itself. It is the largest metropolitan area in the world by population. As the city has continued its sprawl over more than 5,200 square miles, it has been sub-divided into numerous smaller, often self-governing entities, including 23 “special wards” that form the core of the city, three dozen smaller cities, villages and towns, and a series of often far-flung islands, including Minami-Tori-shima (Marcus Island) and the Okinotorishima atoll, both more than 1,000 miles away from central Tokyo. And though it has earned well-deserved recognition as one of the most densely populated cities in the world, many might be surprised to learn that more than one-third of the larger metro area has actually been designated as natural parkland, under the protection of Japan’s government.