Aerial view of Amazon headquarters Amazon’s global headquarters in Seattle spans 8.1 million square feet across 33 buildings.

SEATTLE—Already domiciled at an 8.1-million-square-foot campus in its hometown of Seattle, Amazon is looking for a second headquarters city. The world’s largest online retailer on Thursday said it expects to spend $5 billion building Amazon HQ2 somewhere in North America, and ultimately employ up to 50,000 people there.