Beyoğlu is a municipality and district within Istanbul Province, Turkey, situated on the European side of the city. It occupies an area of 9 km2 and lies directly across the Golden Horn from the historic peninsula of Constantinople, which is now the Fatih district. As a distinct administrative unit, it serves as one of the primary centers for cultural activities, leisure, and entertainment in Istanbul, separated from the old city by the waterway.

The area was originally established during the Byzantine period and was initially known as Sykai or Peran en Sykais, referring to its position on the other side of the Golden Horn. It grew significantly in the Middle Ages as a colony of the Republic of Genoa between 1273 and 1453, when it was ruled by a podestà. The name Pera, meaning across in Greek, was used interchangeably with Galata in European sources until the Ottoman conquest in 1453.

The district encompasses numerous quarters including Galata, Tophane, Cihangir, and Şişhane, connected to the old city via the Galata Bridge and Atatürk Bridge. Notable landmarks include the Galata Tower, built by the Genoese in 1348, and the surviving portions of the medieval citadel walls. İstiklal Avenue serves as the main thoroughfare, while Taksim Square is considered the heart of this multicentric downtown area.

Beyoğlu has historically been a hub for European merchants and diverse communities, including Levantines, Christians, and Jews. It introduced the first street lighting, underground railway, and European-style hotels to Turkey. Today, it features vibrant nightlife, restored historic buildings, and cultural events like the Istanbul Film Festival, attracting visitors with its mix of architectural heritage and modern amenities.

The district had a population of 225,920 as of 2022. Its economy has been shaped by urban renewal and gentrification starting in the 1980s, which led to skyrocketing real estate prices and the return of middle-income residents. Transport access is facilitated by multiple bridges and metro lines, while its location on the European side makes it a central point for tourism and business.