Central Boulevards of Brussels in the context of Boulevard Émile Jacqmain

The Pentagon (French: Pentagone, pronounced [pɛ̃taɡɔn] ; Dutch: Vijfhoek, pronounced [ˈvɛifɦuk] ) or Brussels' city centre is the historical city centre of Brussels, Belgium, within the contours of the Small Ring inner ring road. The Small Ring is located on the site of the second walls of Brussels, which were built in the 16th century. As in most European cities, these walls were replaced by large boulevards at the end of the 19th century.

The Pentagon, within the Small Ring, covers 4.61 km (1.78 sq mi) and is more or less pentagonal or heart-shaped, hence its name. In 2013, 51,566 people lived there, mainly in the Marolles/Marollen district and west of the central boulevards. For the entire City of Brussels, there were 168,576 inhabitants; the majority living outside the Pentagon, in the northern part of the municipality.

The Boulevard Anspach (French) or Anspachlaan (Dutch) is a central boulevard in Brussels, Belgium, connecting the Place de Brouckère/De Brouckèreplein to the Place Fontainas/Fontainasplein. It was created following the covering of the river Senne (1867–1871), and bears the name of Jules Anspach, a former mayor of the City of Brussels.

The Boulevard Anspach is continued to the north by both the Boulevard Émile Jacqmain/Émile Jacqmainlaan and the Boulevard Adolphe Max/Adolphe Maxlaan, forming a "Y" crossroad at the Place de Brouckère. To the south, it crosses the Place de la Bourse/Beursplein about halfway through, and continues towards the Place Fontainas where it becomes the Boulevard Maurice Lemonnier/Maurice Lemonnierlaan.

The covering of the Senne (French: Voûtement de la Senne; Dutch: Overwelving van de Zenne) was the covering and later diverting of the main river of Brussels, Belgium, and the construction of public buildings and major boulevards in its place. Carried out between 1867 and 1871, it is one of the defining events in the history of Brussels.

The Senne/Zenne (French/Dutch) was historically the main waterway of Brussels, but it became more polluted and less navigable as the city grew. By the second half of the 19th century, it had become a serious health hazard and was filled with garbage and decaying organic matter. It was heavily polluted, and it flooded frequently, inundating the lower town and the working class neighbourhoods that surrounded it.