Directly behind Haghia Sophia are the walls shielding the Topkapı Palace complex. Part command centre for a massive military empire, part archetypal Eastern pleasure dome, the palace was the hub of Ottoman power for over three centuries, until it was superceded by Dolmabahçe Palace in 1853. For lavish decor and exquisite location, it rivals Granada's Alhambra. At least half a day is needed to explore Topkapı; given the high entrance fee you might want to take a full day to get your money's worth. If you're pushed for time, the must-see features are the Harem (although there's an extra charge), Imperial Treasury and the views from the innermost courtyard.
Be warned that any part of the Palace may be closed at any time.
The entrance to the palace is via the Imperial Gate (Bab-ı Hümayün), erected by the Sultan Fatih in 1478 and decorated with niches that during Ottoman times were used to display the severed heads of rebels and criminals. The gate leads into the first of a series of four courts that become more private the deeper into the complex you penetrate. The First Court was public and not considered part of the palace proper. It housed a hospital and dormitories for the palace guards, hence the popular name, Court of the Janissaries.
Off to the left is the church of Haghia Irene (Aya Irini Kilisesi), built by Emperor Justinian and so a contemporary of Haghia Sophia.
It has the distinction of being the only pre-Ottoman-conquest church in the city that was never turned into a mosque. Closed most of the time, the church serves as a concert venue during the International Istanbul Music Festival.
Still in the First Court, down the hill to the left, is the superb Archaeology Museum, but the palace proper is entered through the Disneyesque gate ahead. Tickets can be bought just before you reach the gate.
A semi-public space, the enormous Second Court is where the business of running the empire was carried out. This is where the viziers of the imperial council sat in session in the divan, overlooking gardens landscaped with cypresses, plane trees and rose bushes. Where once there would have been crowds of petitioners awaiting their turn for an audience, nowadays there are queues lined up waiting to get in to the Harem, an introverted complex of around 300 brilliantly tiled chambers on several levels, connected by arcaded courts and fountain gardens.
Unfortunately, access is limited: you must wait to join a group that leaves every half-hour and is led through no more than a dozen chambers by an official guide. It's not the ideal way to see the place - locked in a crowd and herded around - but it's the only way. Tickets are sold separately (YTL15), from a window located beside the Harem entrance..
Around from the Harem ticket window, a low brick building topped by shallow domes is the former State Treasury, present home of an exhibition of arms and armour, which is interesting for the contrast between cumbersome, bludgeonly European swords and the lighter Ottoman model. Across the gardens, a long row of ventilation chimneys punctuates the roof line of the enormous kitchens, which catered for up to 5,000 inhabitants of the palace. They contain a collection of ceramics, glass and silverware, much of it imported from China and Japan via Central Asia, along the legendary Silk Route. The earliest pieces are Chinese celadon, particularly valued by the sultans because it was supposed to change colour when brought into contact with poison.
All paths in the Second Court converge on the Gate of Felicity (Bab-üs Saadet), the backdrop for an annual performance of Mozart's Abduction from the Seraglio. The gate also gives access to the Third Court.
The Third Court was the sultan's own private domain. Confronting all who enter is the Audience Chamber (Arz Odası), which is where foreign ambassadors would present their credentials, until the room's role was supplanted by the Sublime Porte. Although the sultan would be present on such occasions, he would never deign to speak with a non-Turk and all conversation was conducted via the grand vizier.
To the right is the Hall of the Campaign Pages (Seferli Koşusu), whose task it was to look after the royal wardrobe. They did an excellent job: there's a perfectly preserved 550-year-old, red-and-gold silk kaftan worn by Mehmet II, conqueror of Constantinople.
Things get even more glittery next door in the Imperial Treasury (Hazine). Many of the items here were made specifically for the palace by a team of court artisans, which at its height numbered over 600. A lot of what's displayed here has never left the confines of the inner courts. Not that too many people outside the sultan's circle would have had much use for a diamond-encrusted set of chain mail or a Quran bound in jade. Items like the Topkapı Dagger, its handle set with three eyeball-sized emeralds (one of which conceals a watch face), are breathtaking in their excessiveness.
More remarkable still are the items in the Privy Chamber. It houses the Chamber of Sacred Relics. To the sound of the Quran being read live, vistors trail around a series of items including Moses' staff, Muhammad's sword, tooth, beard and cloak.
The final and Fourth Court is a garden with terraces stepping down towards Seraglio Point, the protruberance of land that watches over the entrance to the Golden Horn. Buildings are limited to a bunch of reasonably restrained pavilions, while the views over the Bosphorus are wonderful, as are the sea breezes on a sun-beaten summer's day. Most notable is the Baghdad Kiosk, built to celebrate Murad IV's Baghadad Campaign in 1638, its glimmering mother-of-pearl furniture is remarkable. The very last building to be constructed within the palace, the Mecidiye Pavilion (Mecidiye Köşkü), built in 1840, now houses a restaurant and café, notable for its covetable terrace seating.
There are changing exhibitions in various buildings around the year, often celebrating Turkey's diplomatic relationships.