What is william green building?

As an AI language model, I don't have access to specific buildings or locations. However, there is a William Green Building named after William Green, a trade unionist and former president of the American Federation of Labor and Congress of Industrial Organizations (AFL-CIO). The building may refer to a specific structure or be used for buildings owned by unions or labor organizations in honor of William Green. Additional information would require more context and specifics about the building in question.