That Belgium is celebrating its 180th birthday today is clear across the whole country. Bakeries, shops, banks and post offices are staying closed, and the whole country is looking forward to the annual processions at the Koningsplein. A number of senior European figures are also among the eminent attendees each year. Today, figures including Herman Van Rompuy, permanent President of the European Council, will be taking their place in the seats of honour.

The whole country is aware of 21 July being the national Belgian public holiday. However, the fact that not many Belgians know exactly what is so special about this day may appear a little strange. Belgian independence was actually declared on 4 October 1830. So why exactly is 21 July the national public holiday?

After the Belgian revolution in 1830 the then elite wrote a brand-new constitution for their young country. A parliament with elected members and senators was to govern the country.

But the search for a head of state revealed itself to be no simple task. It took around six months before a suitable candidate offered himself for the position, Leopold of Saxony-Coburg-Gotha. On 21 July 1831 he took the oath as the first King of the Belgians. Since then Belgians have celebrated this day, with the taking of the oath as the symbol of independence.

But 21 July is not the King's feast day. Together with the population the Royal Family celebrates King's Day on 15 November. That this complicates matters is probably a typical Belgian phenomenon.

The Belgian political landscape, the federalised structure, the three different national languages and two different public holidays: 180 years of Belgium, but 179 years of monarchy. It seems just a little too complex. But there are characteristics that make Belgium what it is: an abundance of diversity within the borders of a tiny country.