Experience this historic site by following the Fortress Trail
- a walk which takes you to places and buildings which tell of everyday life in a fortress and national, military events.
At Oscarsborg you will find a Spa hotel with a restaurant and coffee-shop, a café with its own candle-making shop, and a pleasant pub overlooking to the guest harbour.
The Drøbak Sound is well positioned for defensive installations. Under King Christian IV, a blockhouse was erected at the Kaholmane islet which was completed in 1643.