Allahabad’s elevation is over 90 m (295 ft) above sea level. The old part of the city, at the south of Allahabad Junction Railway Station, consists of neighbourhoods like Chowk, Johnstongunj, Dariyabad, Khuldabad and many more. In the north of the Railway Station, the new city consists of neighbourhoods like Lukergunj, Civil Lines, Georgetown, Tagoretown, Allahpur, Ashok Nagar, Mumfordgunj, Bharadwaj Puram and others which are relatively new and were built during the British rule. Civil Lines is the central business district of the city and is famous for its urban setting, gridiron plan roads and high rise buildings. Built in 1857, it was the largest town-planning project carried out in India before the establishment of New Delhi. Allahabad has many buildings featuring Indo-Islamic and Indo-Saracenic architecture. Although several buildings from the colonial period have been declared “heritage structures”, others are deteriorating. Famous landmarks of the city are Allahabad Museum, New Yamuna Bridge, Allahabad University, Triveni Sangam, All Saints Cathedral, Anand Bhavan, Alfred Park etc.

Allahabad is in Southern part of Uttar Pradesh, at the confluence of the Ganga and Yamuna . The region was known in antiquity first as the Kuru, then as the Vats country. To the southwest is Bundelkhand, to the east and southeast is Baghelkhand, to the north and northeast is Awadh and to the west is the lower doab (of which Allahabad is part). The city is divided by a railway line running east-west. South of the railway is the Old Chowk area, and the British-built Civil Lines is north of it. Allahabad is geographically and culturally strategically located. Geographically part of the Ganga-Yamuna Doab (at the mouth of the Yamuna), culturally it is the terminus of the Indian west. The Indian Standard Time longitude (25.15°N 82.58°E) is near the city. According to a United Nations Development Programme report, Allahabad is in a “low damage risk” wind and cyclone zone. In common with the rest of the doab, its soil and water are primarily alluvial. Pratapgarh is north of the city, Bhadohi is east, Rewa is south, Chitrakoot (earlier Banda) is west, and Kaushambi, which was till recently a part of Allahabad, is North-West.

Allahabad has a humid subtropical climate common to cities in the plains of North India, designated Cwa in the Köppen climate classification. The annual mean temperature is 26.1 °C (79.0 °F); monthly mean temperatures are 18–29 °C (64–84 °F). Allahabad has three seasons: a hot, dry summer, a cool, dry winter and a hot, humid monsoon. Summer lasts from March to September with daily highs reaching up to 48 °C in the dry summer (from March to May) and up to 40 °C in the hot and extremely humid monsoon season (from June to September). The monsoon begins in June, and lasts till August; high humidity levels prevail well into September. Winter runs from December to February, with temperatures rarely dropping to the freezing point. The daily average maximum temperature is about 22 °C (72 °F) and the minimum about 9 °C (48 °F). Allahabad never receives snow, but experiences dense winter fog due to numerous wood fires, coal fires, and open burning of rubbish—resulting in substantial traffic and travel delays, but the city does not receive snow.[63] Its highest recorded temperature is 48 °C (118.4 °F), and its lowest is −2 °C (28 °F).

Rain from the Bay of Bengal or the Arabian Sea branches of the southwest monsoon[65] falls on Allahabad from June to September, supplying the city with most of its annual rainfall of 1,027 mm (40 in). The highest monthly rainfall total, 333 mm (13 in), occurs in August. The city receives 2,961 hours of sunshine per year, with maximum sunlight in May.

The Ganga-Jamuna Doab, of which Allahabad is a part, is on the western Indus-Gangetic Plain region. The doab (including the Terai) is responsible for the city’s unique flora and fauna. Since the arrival of humans, nearly half of city’s vertebrates have become extinct. Others are endangered or have had their range severely reduced. Associated changes in habitat and the introduction of reptiles, snakes and other mammals led to the extinction of bird species, including large birds such as eagles. The Allahabad Museum, one of four national museums in India, is documenting the flora and fauna of the Ganga and the Yamuna. In order to protect the rich aquatic biodiversity of river Ganga from escalating anthropogenic pressures, development of a Turtle sanctuary in Allahabad along with a River Biodiversity Park at Sangam have been approved under Namami Gange programme.

The most common birds found in the city are doves, peacocks, junglefowl, black partridge, house sparrows, songbirds, blue jays, parakeets, quails, bulbuls, and comb ducks. Large numbers of Deer are found in Trans Yamuna area of Allahabad. India’s first conservation reserve for black buck is being created in Allahabad’s Meja Forest Division. Other animals in the state include reptiles such as lizards, cobras, kraits, and gharials. During winter, large numbers of Siberian birds are reported in the sangam and nearby wetlands.