The historical centre of Briançon is a strongly fortified town, built by Vauban to defend the region from Austrians in the 17th century. Its streets are very steep and narrow, though picturesque. Briançon lies at the foot of the descent from the Col de Montgenèvre, giving access to Turin, so a great number of other fortifications have been constructed on the surrounding heights, especially towards the east.
The Savoyards made two raids into French territory in 1691 and 1692. As a result, Vauban was dispatched to inspect the frontier defences, which had been ill-equiped to deal with the attack from Savoy. He returned to the area in 1700 to check on the progress that had been made since his first visit. When Vauban visited Briançon, work on the defences had already started under a local engineer, Monsieur d'Angrogne in 1692. His work was a crude adaption of the medieval walls, but the flanks of the bastioned trace he attempted to create were very short, being severely restricted by the terrain. Always ready to be flexible, Vauban abandoned conventional principles and his own usual design, and created a layered defence with a Spanish-style false bray for the Embrun front. The defences of the Embrun front are unusual for Vauban in that they employ a tenaille trace in places.
The Pignerol front used a more conventional bastioned trace with demi-lunes and a covered way. High above the town was the citadel, which formed part of the defences. The citadel was practically unapproachable most of the way round, so its defences did not need to follow a bastioned trace - walls and the cliffs would be sufficient to prevent an assault.
Over the course of the 18th century, various other fortifications were constructed at Briançon to protect the nearby heights. These include the Fort des Salettes (originally built in 1700, but much enlarged in the 18th and 19th centuries), Fort des Têtes (a massive fort that is bigger than the town itself, first thought of by Vauban but built after his death), the Fort du Dauphin, the Fort Randouillet and the Fort d'Anjou.
In 2008, several buildings of Briançon were classified by the UNESCO as World Heritage Sites, as part of the 'Fortifications of Vauban' group.
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.