Mostly government departments, as The Hague is the city of government (parliament, departments, residence of the king). The white thing with the black horizontal stripes is the city hall of The Hague.

The royals didn't built high-rise buildings, they stayed in their low-rise palaces in The Hague (two are in use with the royals).

The royals have adjusted at the right moment: William I resigned in 1840 at the moment the protest against his policy of keeping the country on a war footing against Belgium and the national debt threatened to him; William II agreed to liberal constitutions in 1840 and 1848; Wilhelmina managed to become popular through her speeches during the War; Beatrix did a charm offensive to the left-wingers who were against her for marrying a German. The House of Orange always a staunch support with the protestants, who believe in a sort holy bond between the fatherland, Orange and God.

But who will wave from the palace if there is no Queen anymore? ;-)

And you get a live soap opera for all the money spent on the Royals: an old lady who knows about horse racing, an old gentleman who makes politically-uncorrect remarks, a naked prince, a prince who talks to trees, marriages, divorces, scandals etc. etc.