Browsing through the UNESCO list of World Heritage Sites in the Netherlands is always educational. For example: There's this crazy thing called the Defence Line of Amsterdam, and it is exactly what it sounds like.

Built between 1883 and 1920, the Defence line surrounds Amsterdam and was built with the idea of defending the city. The wall extends 135 km around the city, and of course, just beyond the walls you've got the quintessential canals and locks that the country is so known for.

There are different historical spots associated with the Defence line that can be visited, but unfortunately not all year round. For example the Fort Aan Den Ham, located in Uitgeest, will only have its next visitation day on April 27, from 11pm to 4pm. They have various exhibits which include photos and all the fun things a fort should have.

Other forts like the Dutch Coastal Defence Museum, located in the Hoek van Holland, have slightly better opening hours starting in February. A full listing of Defence Line related museums can be found on this website.

Hopefully this helps if you're planning on coming to town and looking for some less well known yet highly fascinating places to see.