Located across the street from 5, the palace is the traditional home of the Belgian royal family, although it's been more than a century since the royal family lived in it. Today the palace functions as the administrative headquarters of the Belgian constitutional monarchy. Here the king receives foreign guests and his staff deals with administrative matters of state that require the monarchy's attention.
Brussels Palace is open to the public every summer after the National Holiday of 21 July until September. We visited in the spring so entering the palace was not an option for us, but if you're there when the palace is open, it looks quite magnificent and worthy of a visit.