Located along the banks of the Yamuna River, around 3 km from Triveni Sangam, the confluence of the Ganges, Yamuna, and Saraswati rivers, the Allahabad Fort is a historic fort in Allahabad, renamed Prayagraj in October 2018, recognised by the Archaeological Survey of India as a monument of national importance. Considering the strategic importance of the location, the massive fort was commissioned by the Mughal Emperor Akbar in 1583, as a solid base to strengthen Mughal control in the region. According to Akbarnama, written by Abu'l-Fazl Ibn Mubarak, also known as Abul Fazl, an Indian historian, the fort was originally named by Akbar as Ilabas, or the Abode of Allaha, which later gradually evolved into Allahabad.

Proudly displaying the blending of Persian and Mughal architectural style, the fort was once considered among the best garrisons in the entire Mughal Empire, and was used as a military base by the British rulers until India gained its independence. With its unrivalled splendour, sophisticated design, spectacular architecture, and excellent craftsmanship, the fort is regarded as one of the most prominent tourist attractions of the city of Allahabad, now known as Prayagraj.

Covering a vast area of about 56 acres (22.66 ha), surrounded by massive walls, enclosing several palatial buildings, courtyards and temples, the fort is equipped with four gateways, flanked by high towers. Among the gates, the Delhi gate, facing the east, has a double archway and a domed chamber above it, while the Khizri Gate, the smallest of the four, facing the south, is equipped with a simple archway and a staircase, leading to the river, which was used by the royal family and the nobles to access the boats and the barges.

The Chalees Satoon Ki Masjid, which faces the west, is the oldest gate of the fort, leading to a mosque with 40 pillars, and also a courtyard containing a fountain, while the north facing Darwaza-i-Shahi, built in Gothic style and containing a drawbridge, is the newest gate of the fort, constructed in 1856, by the British and was used by the British officers and the soldiers.

The enclosure of the fort contains a 10.6 meter high Ashoka Pillar, dates back to the 3rd century BC. The sandstone pillar has inscriptions in Brahmi script, depicting the edicts and policies of Ashoka, as well as a Persian inscription, which was added later by Mughal Emperor Jahangir, claiming to have moved the pillar from Kaushambi to Allahabad. It also contains the Saraswati Koop, a well that is believed to be the source of the mythical Saraswati river, located near the Ashoka Pillar, and is considered sacred by the Hindus.

The Patalpuri Temple, dedicated to Lord Vishnu and located near the Saraswati Koop, is an underground temple, accessed by a narrow staircase. The sanctum or the Garbha Griha of the temple houses an idol of Lord Vishnu, and a hall, containing several other idols and images of Hindu gods and goddesses. Apart from that, the fort complex also contains the Akshayavat, a sacred banyan tree that is believed to be immortal, and is revered by the Hindus, located near the Patalpuri Temple. Today, the tree is surrounded by a wall, and is guarded by the army, since according to a legendary story, the place was used by the locals to commit suicide to attain salvation.

Like the other Mughal forts in India, the Allahabad fort also has a Diwan-i-Khas, and a Diwan-i-Aam. The Diwan-i-Khas, a rectangular hall with a vaulted ceiling and a balcony, ornamented with calligraphy, paintings, jewels, and containing the royal throne, was used by the emperors to hold private meetings with the nobles and the dignitaries, while the Diwan-i-Aam, also a rectangular hall with a flat roof and a colonnade, decorated with banners, flags, lamps, and containing a platform and a podium, was used to hold public meetings and audiences with the commoners. The other important structures in the fort complex include the Jodhabai Palace, located near the Delhi Gate, and built by Akbar for his Rajput wife, Jodhabai, containing a central courtyard and four towers, along with a hall, a chamber, a kitchen, and a bathroom, decorated with floral motifs, geometric patterns, and glazed tiles.

The Zenana Palace, located near the Chalees Satoon Ki Masjid, and built by Jahangir for his wife, the Persian princess, Nur Jahan, is a beautiful example of the Persian architecture. The exquisite palace, decorated with a central dome and four minarets, and containing a hall, a chamber, a balcony, and a garden, is adorned with several paintings, carvings, and beautiful inlays. There is another notable palace in the complex, known as the Rang Mahal, located near the Khizri Gate, which is a stunning example of the Iranian architecture. The palace, crowned with a central dome and equipped with six arches, containing a hall, a chamber, a terrace, and a fountain, embellished with murals, mosaics and mirrors, was built by Aurangzeb for his wife, Dilras Banu Begum, a princess of Safavid Iran. Another palace, the Moti Mahal, was built much later by the Marathas for their queen, Ahalyabai Holkar. The palace, located near the Darwaza-i-Shahi, and built in a simple Maratha architectural style with a flat roof, and containing a hall, a chamber, a store, and a kitchen, is furnished with wooden furniture, carpets, and curtains. Apart from the above, the Jami Masjid, a modest mosque, located near the Rang Mahal and complete with a courtyard, a minaret, a pond and a mihrab, a chamber indicating the direction of Mecca, was built by Aurangzeb for his personal use for prayers.