An artificial fortress island just eight kilometres from Copenhagen - with its own marina and berths directly beneath the fort: Flakfortet is up for sale. The sea fort is set to change hands for 74.75 million Danish kroner (around 10 million euros) after almost 25 years in Swedish hands. However, monument protection, public accessibility and the question of future use make the deal complex. What buyers can expect - and how things could continue on site.