It's a nationwide Flea market!
As part of the mega birthday party each year, loads of folks bring their second hand goods to the city parks, and sidewalks.
This is the ONE day a year that folks can sell their stuff without paying Taxes
Visit the link HERE for Maastricht's Market ( I included this one, as it's closest to Germany at 2.5 hours drive)
Visit the link Here for Amsterdam's Market (aprox 6 hour drive from K-town Germany)
Taken from the Travelsignposts website:
Vrijmarkt – Flea Market
A big feature of the Koninginnedag celebrations is the vrijmarktor “freemarket”. On this one day people all over the country are allowed to sell things in the streets without having to pay value added tax on their sales! People are allowed to set up stalls or have their goods on blankets in the parks or on sidewalks. It’s not just the car boot sales or flea market sales that are exempt from tax, commercial traders benefit from this one day of tax-free sales. Naturally, the amount of sales clocked up on this one day is huge.* Please note the maps on the website for maastricht, and print in advance. It lists the location and also that of restrooms.
Be prepared for Road closures in the city..Check on parking ahead of time if possible.
Plan on bringing backpacks, market carts etc... to carry your goods through crowds. =)
Wear good walkin shoes, bring small Euros for easy purchasing.
And dont' forget to wear ORANGE~!