The most unique things about The Netherlands are its name and language.
Other well known uniqueties in Holland:
it's legal to smoke weed or to buy it (not to grow it)
it's legal to prostitutes or to be one
it's legal to marry with someone of your own sex
it's legal to activate death if you're very ill or in pain
it's the home country for Johan Cruyff, Rembrandt and Van Gogh
The people and areas of the Netherlands make it a unique place. There are no roads in the village of Giethoorn and people travel by water through canals. One thing that makes the Netherlands unique is that it has two capitals.