Diwan-i-am and the great courtyard
Once through the Amar Singh Gate, ignore, for the time being, the complex of ornately carved buildings on your right and continue straight ahead through a second gate to a spacious enclosure dominated by the graceful Diwan-i-Am (Hall of Public Audience). Open on three sides, the sandstone pillared hall, which replaced an earlier wooden structure, was constructed by Shah Jahan in 1628 and, after use as an arsenal by the British, was restored in 1876 by Sir John Strachey. Three rows of white polished stucco pillars topped by peacock arches support a flat roof; the elegance of the setting would have been enhanced by the addition of brocade, carpets and satin canopies for audiences with the emperor. The ornate throne alcove is inlaid in marble decorated with flowers and foliage in bas-relief, and connects to the royal chambers within. Encrusted with diamonds, rubies and emeralds, the Peacock Throne which it was built to house was removed to the Red Fort in Delhi when Shah Jahan shifted his court there; it eventually ended up in Persia after the fort was looted by Nadir Shah in 1739. Adjacent to the alcove, the Baithak, a small marble block, is where ministers would have sat to deliver petitions and receive commands. This is also where trials would have been conducted, and justice speedily implemented. The East India naval commander, William Hawkins, who attended Jehangir's court between 1609 and 1611, noted the presence next to the emperor of his "master hangman, who is accompanied with forty hangmen, with an hatchet on their shoulders; and others with sorts of whips being there, readie to do what the King commandeth".

An incongruous intrusion in the centre of the great courtyard is a gothic Christian tomb marking the grave of John Russel Colvin , the Lieutenant-Governor of the Northwestern Provinces who died here during the Mutiny of 1857.

The royal pavilions
Clustered around a high terrace overlooking the river, the royal pavilions were designed to catch the cool breezes blowing across the Yamuna - and for ease of access to a water supply. The Macchi Bhavan (Fish Palace), approached through the alcove in the Diwan-i-Am, has suffered through the ages. During the period of Jat control, the Maharaja of Bharatpur removed some of its marble fixtures to his palace in Deeg; later, the zealous evangelist Lord William Bentinck (governor-general from 1828-35) auctioned off much of the original mosaic and fretwork, including parts of the Hammam-i-Shahi , the royal bath. The palace was once strewn with fountains and flowerbeds, interspersed with tanks and water channels stocked with fish for the angling pleasure of the emperor and courtiers. In the northwest corner of the enclosure, the exquisite little Nagina Masjid (Gem Mosque) is entirely made of marble. Capped with three domes and approached from a marble-paved courtyard, it was built by Shah Jahan for the ladies of the zenana (harem). Below it, overlooked by a beautiful marble balcony with carved lattice screens and peacock arches, is the Inner or Zenana Mina Bazaar , where ladies of the court could look at goods such as silk, jewellery and brocade offered by merchants, without being seen themselves.

The Chittor Gate , salvaged by Akbar as a trophy from the horrific sacking of the Rajput stronghold of Chittor (now Chittaurgarh in southeast Rajasthan) and installed in 1568, leads to the Mandir Raja Ratan , erected in 1768 during the Jat occupation of the fort. Past this is the Hall of Private Audience, the Diwan-i-Khas , where the emperor would have received kings, dignitaries and ambassadors, and where recently completed paintings or architectural plans were submitted for his approval. Erected in 1635, the building was badly damaged when it came under bombardment by General Lake in 1803, but the hall - with its ornate pillars and arches inlaid with lapis lazuli and jasper - survives. Two thrones adorn the large terrace in front of the Diwan-i-Khas, one of black slate and the other of white marble. Shah Jahan apparently took his evening repose in the white throne; from the black one, the emperor would amuse himself by watching elephant fights in the eastern enclosure.

A doorway from the rear of the Diwan-i-Khas leads to a two-storeyed pavilion or tower known as Musamman Burj , famous in Moghul legend as the spot where, in the open octagonal chamber atop the highest of the riverside bastions, Shah Jahan caught his last glimpse of the Taj Mahal before he died. Surrounded by a veranda, the elegant pavilion has a lattice-screen balustrade with ornamental niches; exquisite pietra dura inlay covers almost every surface, and a marble chhatri adds the finishing touch. In front of the tower a courtyard, paved with marble octagons, centres on a pachisi board where the emperor, following his father's example at Fatehpur Sikri, played a rather bizarre version of the game (a form of backgammon) using dancing girls as pieces.

To the south of Musamman Burj lies the marble building known as Khas Mahal (Private Palace), possibly used as a drawing room or the emperor's sleeping chamber. Designed essentially for comfort, it incorporates cavities in its flat roofs to insulate against the searing heat of an Agra summer, and affords soothing riverside and garden views. The palace is flanked by two Golden Pavilions, their curved roofs covered with gilded copper tiles, in a style inspired by the thatched roofs of Bengali village huts. Stretching in front of the Khas Mahal to the west is Anguri Bagh (Grape Garden), a miniature charbagh , with its quarters delineated by wide marble pavements. In the northeast corner, the Shish Mahal (Palace of Mirrors) was where royal women bathed in the soft lamplight reflected from the mirror-work mosaics that covered the walls and ceiling. Connected to the Khas Mahal by an extensive corridor, the Shah Jahani Mahal (Shah Jahan's Palace) is supported by wooden beams; its four chambers were originally painted in bright colours and embossed in gold.

The palaces of Jahangir and Akbar
Immediately southwest of the Shah Jahani Mahal is the robust, square Jahangiri Mahal . This red-sandstone palace, built either by Jahangir or by Akbar on his son's behalf, is almost entirely Hindu in its interior design. In the Assembly Hall, carved ornamental brackets support beams, wide eaves and ceilings with struts; the serpentine form being emitted from a dragon's mouth is reminiscent of a Gujarati temple.

Rooms to the west are thought to have been the temple and drawing room of Akbar's Rajput wife Jodhbai. Below the palace, three storeys of basement chambers were used to escape the heat. Jahangir's Hauz or cistern, a giant bowl made in 1611 from a single block of porphyry and inscribed in Persian, was unearthed in the nineteenth century and stands in the courtyard in front of the Jahangiri Mahal. Filled with rose water, it would have been used by the emperor as a bathtub.

Returning towards Amar Singh Gate to the left, an assembly hall, a veranda overlooking the river and excavations are all that remain of the southernmost palace, the once extensive Akbari Mahal , built in 1571.