Three storied outbuilding (1782 -1783, completion – after 1845 to 1847 and during after 1867 to 1873). In its original form – a one-story building, maintained in the classical style (architect – J.-A. Munz). The building is rectangular in plan, with a hipped roof, the side facades of which were decorated with wooden phials, typical of the Gothic style. Until 1845 the one-story outbuilding was connected to the palace by an order gallery.
Approximately it is possible to determine the dating of changes in the outbuilding only by the time of the appearance of four projections, which were not completed at the same time, as well as the second and third floors of the building.
The first, probably, was the projection on the left flank that was completed or built after 1845 to 1847 on the site of the former three-storied gallery entrance to the order gallery. The risalit was decorated with a portico supported by six wooden columns and an open terrace at the level of the third floor. With the completion of this risalit, the side palace facade of the outbuilding was quite richly decorated and actually became the front facade of the third floor. Its architecture echoes the architecture of the side facade of the palace. It is decorated with four blades which “support” multyprofiled cornice, vertically divide facade and visually increase the height. In the places over juts the cornice imitated capitals of the columns. Above the twin windows and doors witch have ogive completions and framed by on archivolt, there are rectangular edges, decorated with stylized flowers in the corners. Huge window and door openings visually facilitate perception of volume of an outbuilding. Side facade of the building completes the triangular pediment with a three-section window with a lanced ending, framed by an archivolt. Along the perimeter of the pediment is decorated with a drawn multi-profile cornice. The ridge the roof crowns the phial.
At the completion of the second projection in the facade, located on the site of an existing single-storey portico with columns manor-house it was considerably strengthen interior walls. The architectural decoration of this risalit became an immitated simulated portico, which rested on six wooden half-columns protruding from the plane of the wall of the third floor. Between half-columns there were three windows. Behind this ledge, a part of the outbuilding until 1847 still remained one-story. The completed ledges on the level of the third floor were connected by an open terrace, which was supported by five high-rise columns.
Joint two risalits visually limited the overall size the part of the outbuilding, and after superstructure by second and third floors of the main facade of the outbuilding that overlooked the square between building almost repeated the Palace shape P-shaped in plan. Bringing construction of the outbuilding in height was in such way so that the level of the second floor was raised to the height of the sole of the front first floor of the palace, and the level of its cornice the roof ridge of the outbuilding nose.
On the left flank of the building, at place of the entrance vestibule, after 1861 the third risalit appeared. It had a flat roof, the corners of which – the columns and with onion-like finishing and railings, leaned obviously at the classic balusters. Along the perimeter of the roof completion – entire barriers in the form of kokosnyk. From the completed risalit through the two-field door there was an exit to open terraces of the third floor.
The last, fourth risalit on the right flank of the building appeared till 1873. At the corners of the ledge completed speech on the third floor level there were dual columns (now there are none).
The roofs of wooden ledges finished by triangular pediments, with three windows of the canced form, the average of which was larger and by size fialas. Perhaps after 1960s windows on in the facade pediments were replaced in foursections, square by shape, which had broken the architectural harmony of the building.
The rear facade of the outbuilding has only window openings of the level of each of the three floors. Window openings on the first and second floors are symmetrical, while on the third floor they are not. A part of the third floor between the first and third risalits has six dual and one single window, while between the third and fourth risalits – single. Visually it’s noticeable that a part of the wall on the third floor on the left flank is pulled out the level of the existing walls of the first and second floors, which suggests that this part was completed without proper architectural oversight, and possibly without any project.
The horizontal dividing of the wall surface of the side, river, facade is achieved through nine windows which also provide corresponding symmetry. Among them there are three false windows; one of them is implicitly authentic.
Window openings of the first and second floors are rectangular. Their frame the same, as bordering doorways, which is made of lime and clay, creates peculiar stucco decoration. Third floor window openings, dual and single, have a form of arrow-shaped arches and accented by rectangular edges; the third floor of the fourth risalit from the side of the inter-building square is decorated with a three-part Venetian window.
The decorative element of the main, back and side, river , facades became multi-profile eaves under the roof and stepped – interfloor.
A three-storey wing conducted pre- and superstructure remains rectangular in plan, with performances on the main facade.
Planning of building is different on all floors. On the first one it’s mostly endlade corridor in the risalits ; on the second – enfilade and mostly corridor with a bilateral arrangement of rooms; on the third – enfilade on the perimeter of the building.
The art gallery is on the third floor.