Jakub Fontana (1710 – 13 April 1773) was a Polish architect of Swiss Italian origin, a practitioner of the Baroque and Neoclassical styles.

Having studied the latest trends and styles, he brought back with him stencils from which he drew inspiration to the end of his professional life.

The architectural decoration of the aisles formed in a pillared layout can be attributed to Fontana, who designed them when he returned to Poland in 1737.

Creatively independent work by Jacob Fontana started only in 1737, after he returned from the eye-opening trip to northern Italy, Rome, Paris and Vienna.

From 1742, the Grand Marshal of the Crown Franciszek Bieliński employed Fontana for major public and private projects.

For a short time he was employed by Eustachy Potocki, when he was involved with his reconstruction of his Rococo palace in Radzyń Podlaski, then for the Lubomirski family, and the bishop of Załuski.

After Stanisław August Poniatowski ascended the Polish throne, Fontana was appointed as the first architect to the king, undertaking major works relating to the Royal Castle, Warsaw and other important state buildings.