Dalarö fortress was built by Charles X Gustav of Sweden in 1656. It replaced an old structure from 1623. In 1683 the fortress was renovated by Erik Dahlbergh and the renovations were completed in 1698. The fortress has never been under siege and therefore well-preserved. It was decommissioned by the military in 1854. Today the building is a museum and it contains a restaurant.References:
The Odeon of Herodes Atticus is a stone theatre structure located on the southwest slope of the Acropolis of Athens. It was built in 161 AD by the Athenian magnate Herodes Atticus in memory of his wife, Aspasia Annia Regilla. It was originally a steep-sloped theater with a three-story stone front wall and a wooden roof made of expensive cedar of Lebanon timber. It was used as a venue for music concerts with a capacity of 5,000. It lasted intact until it was destroyed and left in ruins by the Heruli in 267 AD.
The audience stands and the orchestra (stage) were restored using Pentelic marble in the 1950s. Since then it has been the main venue of the Athens Festival, which runs from May through October each year, featuring a variety of acclaimed Greek as well as International performances.