Carnuntum was a Roman Legionary Fortress and also headquarters of the Pannonian fleet from 50 AD. After the 1st century it was capital of the Pannonia Superior province. It also became a large city of 50,000 inhabitants. In Roman times Carnuntum had a history as a major trading centre for amber, brought from the north to traders who sold it in Italy; the main arm of the Amber Road crossed the Danube at Carnuntum. Its impressive remains are situated on the Danube in Lower Austria in the Carnuntum Archaeological Park extending over an area of 10 km² near today's villages of Petronell-Carnuntum and Bad Deutsch-Altenburg.
The remains of the civilian city extend around the village Petronell-Carnuntum. There are several places to see in the city: Roman city quarter in the open-air museum, palace ruins, amphitheatre, and Heidentor.
Some way outside the city was a large amphitheatre, which had room for about 15,000 spectators. A plate with an inscription found at the site claims that this building was the 4th largest amphitheatre in the whole Roman Empire.
Between 354 AD and 361 AD, Heidentor, a huge triumphal monument was erected next to the camp and city. Contemporary reports suggest that Emperor Constantius II had it built to commemorate his victories. When the remains of Carnuntum disappeared after the Migration Period the monument remained as an isolated building in a natural landscape and led Medieval people to believe it was the tomb of a pagan giant. Hence, they called it Heidentor (pagan gate).References:
Sirmione castle was built near the end of the 12th century as part of a defensive network surrounding Verona. The castle was maintained and extended first as part of the Veronese protection against their rivals in Milan and later under the control of the Venetian inland empire. The massive fortress is totally surrounded by water and has an inner porch which houses a Roman and Medieval lapidary. From the drawbridge, a staircase leads to the walkways above the walls, providing a marvellous view of the harbour that once sheltered the Scaliger fleet. The doors were fitted with a variety of locking systems, including a drawbridge for horses, carriages and pedestrians, a metal grate and, more recently, double hinged doors. Venice conquered Sirmione in 1405, immediately adopting provisions to render the fortress even more secure, fortifying its outer walls and widening the harbour.
Thanks to its strategical geographical location as a border outpost, Sirmione became a crucial defence and control garrison for the ruling nobles, retaining this function until the 16th century, when its role was taken up by Peschiera del Garda.