In ancient and medieval times the whole town was surrounded by walls with ten gates. Most were pulled down in the early 19th century, but a section survives between the Twin Gate and the Giardini square. The Twin Gate, named for its two arches, was built between the 2nd and 3rd centuries and leads to the Archaeological Museum and the castle above.
Porta Gemina (Twin Gate)
Roman twin-arched gate leading to castle and museum