Especially for Maria Nikolaevna, who had a medical problem with her legs, a ramp was built in the right wing of the building which took you to any floor of the building. The ramp was decorated with various plants, which made the walk enjoyable. The right wing of the building belonged to Maria Nikolaevna, and her quarters included the reception hall, living room, office, bedroom, boudoir, dressing room, and oval or corner offices. Rooms along the main facade had a view of the St. Isaac's Square.

There was a grand reception hall, billiard room, living room, study (on display was a collection of weapons and minerals), and a Turkish cabinet. A chapel for the Duke was constructed in the first floor. The chapel was decorated with stained glass, brought from Munich, the homeland of Duke Maximilian.

In addition, on the first floor there were children’s rooms and apartments for the tutors. The largest room of the palace, a sports hall, was also located on the first floor.

The house church of St. Nicholas was on the attic floor of the palace. The main staircase of the palace was decorated with statues of ancient heroes. An original stucco ornament of interlaced letters formed the name "Maria".

Work on the construction of the palace proceeded rapidly. In 1845, the young couple settled in the palace. At that time the palace officially received the name of the Mariinsky Palace. The palace was opened to the public for inspection.

In 1852, Duke Maximilian died. Maria Nikolaevna lived in his palace until her death in 1876. Mariinsky Palace was inherited by their children, Eugene and George Leuchtenberg. They sold the palace to pay their debt.

In 1884, the Mariinsky Palace was purchased by the State Treasury for 3 000 000 rubles to be paid in installments over thirty years. Since 1885 it housed a State Council and the Committee of Ministers of the Russian Empire. In addition, it housed an Office of the War Department. The interior of the palace was remodeled to suit the new owners.

For example, the rotunda was adapted for the meetings of the State Council. The Cabinet of Duke Maximilian was converted into an office of the chairman of the State Council. Concert halls and oval offices were converted into meeting rooms for the Cabinet and the Department of Civil and Religious Affairs.

Upon Marie death, her children sold the palace back to the Crown, and for some after that it housed the Council of the Empire.

In the Soviet times, the building housed the Executive Committee of the Leningrad City Council - on the facade, under the national emblem of the Russian Federation, were models of the Gold Star, the four orders conferred on the city, and the medal "For the Defence of Leningrad".

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