Skåne Defense Line

The bunkers I visited were within a short distance of the nearby village of Smygehamn, and required crossing the edge of farmers' fields, however it does not seem like anyone will stop you from visiting.

My understanding is also that Swedish law allows passage over land even if it is owned, provided it's not part of a dwelling.

As for the bunkers, the biggest issue is all the potential tripping and falling hazards around, and the door in the one dome structure seems like it could potentially be hard to open from the inside if it somehow was closed while one was exploring inside.

Other than that, hope you don't mind spiders.

A series of concrete fortifications constructed by Sweden in the 1930s and early 40s as they correctly foresaw the outbreak of the Second World War.

The line was built along the southernmost coast in case of a German invasion by sea. Of course, no such invasion came, and Sweden remained neutral.

It was further reinforced for use during the Cold War, with more bunkers added, now with concerns about the Soviets in mind. With the end of the Cold War the bunkers were abandoned.

They were never continuously manned, but rather set in place to be manned when necessary if tensions reached the point where an invasion was thought to be imminent.