Istanbul's been a busy trading center from the start, so it needed to be well-protected. This imposing wall helped fortify the ancient Byzantine capital. The wall sealed off the city, protecting it on the one side where the water didn't. Dating from the fifth century, these ramparts stood strong against both Catholic Europe from the West and the Muslim forces from the East… until 1453.

Finally, the Ottoman Turks, who for centuries had been on the rise and chipping away at the Byzantine Empire, broke through the walls. They established the city as the capital of their growing empire and transformed Christian Constantinople into a Muslim city.

Our storybook image of the Ottomans — sultans, harems, eunuchs — is best imagined here, in the Topkapı Palace. Built in the late 15th century, this was the power center of the Ottoman Empire for almost 400 years. Its buildings form a series of courtyards — the outer being used for public functions. The farther in you go, the more private the rooms.

Among the most private was the harem. The word "harem" means "forbidden" in Arabic. It's the huge suite where the sultan lived with his wives, female slaves, and children.

Lale: This is the largest room in the harem. It was the entertainment room, and used for activities like the wedding of the sultan's daughters. This was the divan that the sultan used as a throne. The divans by the window were used by the queen mother and the wives of the sultan, and the musicians used the balcony up above. But when I say "a party," do not imagine a public event. It was rather for the family of the sultan.
Rick: So, just a small family affair. The sultan, his mom, his wives, and his girlfriends.
Lale: His favorites. The whole purpose of the harem was to provide future heirs to the throne, to the Ottoman throne. But most of the tourists think that it was a party place, a fantasy place — it was not. It was an institution that had its own rules, it was very well-regulated, and these rules were very strict. The sultan was not above these rules.
Rick: So, the sultan didn't just come in and pick a girl.
Lale: Definitely not. It was the queen mother, mother of the sultan, mostly, that decided what should happen in the harem, and it was, again, the queen mother that decided whom the sultan socialized with.

And of course the Sultan enjoyed a state of the art bathroom complete with hot and cold running water.

Bathed in light from these exquisite stained-glass windows, this is where the sultan relaxed, entertained and savored the sumptuous luxury his power provided.

Some of the sultan's opulence is still on display in the palace museum. The exquisite Topkapı dagger wows tourists with its dazzling diamonds and golf-ball-sized emeralds. Clearly the Ottomans in their heyday were a wealthy power.

The palace is also a holy spot for Muslims containing relics of Muhammad and other prophets — some of whom are revered in both the Bible and the Koran. This contains what's considered to be the arm of St. John the Baptist. And here's John's skull inside this jeweled case. For Muslims the most precious relics are those of Muhammad: his bow and sword, exquisite cases containing his tooth, some hair, and his holy seal. And in the adjacent room a hafiz — that's someone who's memorized all 6,000 verses of the Koran — is part of a team that sings verses from the Muslim holy book 24 hours a day, seven days a week.

For generations, Europe dreaded the Ottoman threat. They were on the march, even knocking on Vienna's fortified door. But through the 19th century a combination of corruption, incompetent sultans, and an antiquated medieval organization all contributed to the eventual fall of the Ottoman Empire.