Skansen Kronan is a redoubt built in the later half of the 17th century according to the plans of Erik Dahlberg. Skansen Kronan was introduced in 1698 and was fitted with 23 guns. The roof was not completed until 1700. Skansen has 4-5 metre thick walls made of granite, gneiss and diabase. Skansen Kronan was never attacked and the cannons on the inside have never been used.
The fortress and the twin counterpart, Skansen Lejonet, were built as part of the defenses against possible Danish attack on Gothenburg from the south, and thus had a similar purpose as the Älvsborg Fortress.
The fortress - originally built outside the city walls - is today situated in the city centre of Gothenburg on a hill in the city district of Haga. It was used as a military museum until 2004. Today Skansen Kronan is a private facility for conferences and private parties.
References:The ancient Argos Theater was built in 320 BC. and is located in Argos, Greece against Larissa Hill. Nearby from this site is Agora, Roman Odeon, and the Baths of Argos. The theater is one of the largest architectural developments in Greece and was renovated in ca 120 AD.
The Hellenistic theater at Argos is cut into the hillside of the Larisa, with 90 steps up a steep incline, forming a narrow rectilinear cavea. Among the largest theaters in Greece, it held about 20,000 spectators and is divided by two landings into three horizontal sections. Staircases further divide the cavea into four cunei, corresponding to the tribes of Argos A high wall was erected to prevent unauthorized access into the theatron and may have helped the acoustics, but it is said the sound quality is still very good today.
Around 120 CE, both theaters were renovated in the Roman style.