The Palace of the Seminary, located behind the Cathedral, was built by the architect Carlo Martinuzzi the beginning of the XVIII century. The building boasts ornate entrance portal, which in 1714 was carved in the workshop of Luke Mason Mislay. On the sides of the portal are statues of Herakles work Angelo Putti. In XVIII-XIX centuries the Palace was added several outbuildings.

In the Palace of the Seminary is a two-storey Seminary library, the first public library of Ljubljana, founded in 1701, at the initiative of members of the Academy. Being public for 50 years, the library was then transferred to the theologians. The ceiling, painted by Giulio Calio in 1721, and furniture made of real oak, is manufactured by cabinetmaker by Josip Vergata, the Seminary library is one of the most beautiful Baroque monuments in Slovenia. The library preserves many valuable manuscripts and printed works.