Balilla was the lead ship of her class of four submarines built for the Regia Marina (Royal Italian Navy) during the late 1920s.

[1] For surface running, the boats were powered by two 2,450-brake-horsepower (1,827 kW) diesel engines, each driving one propeller shaft.

The submarines were also fitted with an auxiliary diesel cruising engine that gave them a speed of 7 knots (13 km/h; 8.1 mph) on the surface.

They were also armed with a single 120-millimeter (4.7 in) deck gun, forward of the conning tower, for combat on the surface.

[1] Ballila was laid down on 12 January 1925 at the Odero-Terni-Orlando shipyard in Muggiano, La Spezia.