Directly north of (ie behind) Haghia Sophia are the walls shielding the imperial enclave of Topkapý Palace. Part command centre for a massive military empire, part archetypal Eastern pleasure dome, the palace was the hub of Ottoman power for more than three centuries, until it was superseded by the Dolmabahçe Palace in 1853. In terms of lavish decor and exquisite siting, it rivals Granada's Alhambra and beats hands down almost anything else in Europe. At least half a day is needed to explore the place fully, although given the high admissions you might want to take a full day over it to get your money's worth. If pushed for time, the must-see elements are the Harem, Imperial Treasury and the views from the fourth and innermost courtyard. Entrance is via the Imperial Gate (Bab-i Hümayun), 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 Justinian and thus 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 Archaeological Museum, but the palace proper is entered through the Disneyesque gate ahead. Tickets can be bought on the right, just before you reach the gate, beside the Executioner's Fountain, where the chief axeman washed his blade after carrying out his grisly work. The heads of his victims were also displayed on top of the truncated columns that stand on either side of the fountain. 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 severely 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, 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, interesting for the contrast between cumbersome, bludgeonly European swords and the lighter, more deadly-looking 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 now contain a collection of ceramics, glass and silverware, much of it originating from China and Japan and imported 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), which serves as the backdrop every year for a performance of Mozart's Abduction From the Seraglio - again, part of the International Istanbul Music Festival. The gate also gives access to the Third Court. The Third Court was the holy of holies, the sultan's private domain. Confronting all who enter is the Audience Chamber (Arz Odasý), which is where, until it was supplanted in the role by the Sublime Porte , foreign ambassadors would present their credentials. 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. Off to the right is the Hall of the Campaign Pages (Seferli Koðuþu), 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