Born in Warsaw in a Jewish family of Sephardi origin, descended from Salomon Calahorra, the royal physician of two kings of Poland: Sigismund II Augustus and Stephen Báthory. Hilel was son of Mendel Lewkowicz Landsberg, a tradesman in Warsaw, and Lea née Lewek.
Hilary Landsberg married Hana Mendelsburg (1838–1904) and had two sons Alexander (Abram Lajb) (1858–1924) and Felix (Fishel) (1868–1923), as well as 6 daughters. In 1857, he created a small cloth-manufacture in Tomaszów Mazowiecki with 10 hand-looms. Step by step he modernized means of production.
In 1881-1883 he built a new, large cloth-factory in the town (Gustowna street 46), introducing the steam propulsion.
In 1894 he built the finish-work factory and the storehouse of wool. In 1896, he electrified his factory.
He employed more than 300 workers in H. Landsberg’s factory.
