Islamabad (/ɪzˈlɑːməbæd/ ^ⓘ; Urdu: اسلام‌آباد, romanised: Islāmābād, lit. 'City of Islam', [ɪsˈlɑːmɑːbɑːd] ^ⓘ) is the capital city of Pakistan. It is the country's tenth-most populous city with a population of over 1.1 million, and is federally administered by the Pakistani government as part of the Islamabad Capital Territory. Built as a planned city in the 1960s and established in 1967, it replaced Karachi as Pakistan's national capital.

The Greek architect Constantinos Apostolou Doxiadis developed Islamabad's master plan, in which he divided it into eight zones; the city comprises administrative, diplomatic enclave, residential areas, educational and industrial sectors, commercial areas, as well as rural and green areas administered by the Islamabad Metropolitan Corporation with support from the Capital Development Authority. Islamabad is known for its parks and forests, including the Margalla Hills National Park and the Shakarparian. It is home to several landmarks, including the country's flagship Faisal Mosque. Other prominent landmarks include the Pakistan Monument and Democracy Square.

Rated as Gamma + by the Globalization and World Cities Research Network, Islamabad has one of the highest costs of living in Pakistan. The city's populace is dominated by both middle- and upper-middle-class citizens. Islamabad is home to more than twenty universities, including Bahria University, Quaid-e-Azam University, PIEAS, COMSATS University, and NUST. It is also rated as one of the safest cities in Pakistan and has an expansive RFID-enabled surveillance system with almost 2,000 active CCTV cameras.

The name Islamabad means City of Islam. It is derived from two words; Islam and abad. The Arabic word Islam means "submission [to God]" as it refers to the religion of Islam, Pakistan's state religion, and the Persian suffix -abad means cultivated place, indicating an inhabited place or city. During the course of early modern period, the name was used in the Mughal era, by the emperor Aurangzeb who named many towns in the Indian subcontinent after it. According to a history book by Muhammad Ismail Zabeeh, teacher and poet Qazi Abdur Rehman Amritsari proposed the name of the city.

Occasionally in writing, Islamabad is colloquially abbreviated ISB. Such usage originated in SMS language, in part due to the IATA location identifier for the Islamabad International Airport.

Islamabad Capital Territory, located on the Pothohar Plateau of the northern Punjab region, is considered one of the earliest sites of human settlement in Asia. Some of the earliest Stone Age artefacts in the world have been found on the plateau, dating from 100,000 to 500,000 years ago. Rudimentary stones recovered from the terraces of the Soan River testify to the endeavours of early man in the inter-glacial period. Items of pottery and utensils dating back to prehistory have been found.

Excavations by Dr. Abdul Ghafoor Lone reveal evidence of a prehistoric culture in the area. Relics and human skulls have been found dating back to 5000 BCE that indicate the region was home to Neolithic peoples who settled on the banks of the Soan and who later developed small communities in the region around 3000 BCE.

The Indus Valley civilisation flourished in the region between the 23rd and 18th centuries BCE. Later the area was an early settlement of the Aryan community which migrated into the region from Central Asia. Many great armies such as those of Zahiruddin Babur, Genghis Khan, Timur and Ahmad Shah Durrani crossed the region during their invasions of the Indian subcontinent. In 2015–16, the Federal Department of Archaeology and Museums, with the financial support of National Fund for Cultural Heritage, carried out initial archaeological excavations and unearthed the remains of a Buddhist stupa at Ban Faqiran, near the Shah Allah Ditta caves. The stupa was dated to between the 2nd and 4th centuries CE.