Anheuser-Busch InBev is the largest brewing company in the world, and its global headquarters are in Leuven, a Flemish university town of modest size. Multinationals of that scale usually end up in London, Amsterdam or a tax-efficient holding jurisdiction. This one stayed where the brewery was.
The address records a direction of travel that is easy to get backwards. The 2008 combination that produced the current company is often remembered as an American brewer buying a European one. It was the other way round. InBev, itself the product of a merger between Belgium's Interbrew and Brazil's AmBev, acquired Anheuser-Busch of St Louis. The Leuven headquarters is where the acquiring side already was.
The company is a serial acquirer by design. Its growth has come from buying brewers and applying a cost discipline to them rather than from inventing beers, and the model requires a steady supply of targets and a tolerance for the debt used to buy them. That is a strategy with a clear ceiling: at some point there are no large independent brewers left to buy, and the question becomes what a very efficient operator does when the acquisitions stop.

