Felsenburg castle was probably built in the 12th century for the Freiherr of Kien. The castle was built on a rocky spire above the road over the Gemmi pass into Valais. It was inherited, along with the rest of the Herrschaft of Frutigen, by the Freiherr of Wädenswil in 1290. The Freiherr of Turn acquired it from Wädenswil in 1312. It was mentioned in a record in 1339 as the castrum de Petra. It was again mentioned in 1368 as Stein, German for Stone. In 1400, Bern acquired the castle along with the rest of the Herrschaft. They abandoned Felsenburg and allowed it fall into ruin.
Currently, only the rectangular main tower and remnants of the outer walls are still standing.
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.