Castello is the largest of the six sestieri (districts), and the only one not facing onto the Grand Canal. More than half of Castello is situated within Arsenale, the naval base, which occupies over one-fifth the area of Venice. This gentrified maritime neighbourhood feels busy but casual. Castello’s side streets are laid back, with small boats lining canals criss-crossed by laundry. Semiannual exhibitions add a strong artsy current to the Arsenale area. Via Garibaldi in Castello, with its shops and bars, has one of Venice's rare straight and wide boulevards. When a large ship turns around the Lido to enter the Giudecca Canal, the startling sight creates an illusion that it will run aground right on Via Garibaldi! Families treasure Giardini near the island's tip, green with rare trees and grass, and Riva degli Schiavoni is a popular spot for Venetians to take a stroll to watch the sunset.