With the death of Maria Domitilla in 1867, the property ownership passed to her son, Commander Felício Pinto de Mendonça e Castro.

[2][3][5] In 1880, the residence was put up for auction and bought by the Diocesan Mitra, which installed the Episcopal Palace and made reforms to the structure, such as the construction of a chapel and a crypt under the main altar.

The storefronts on the main façade were eliminated, and the series of three openings on the first floor, under the largest balcony, was restored to accommodate the use of the store of the Companhia Paulista de Gás (formerly The São Paulo Gaz Company).

[2] On June 15, 1971, the Solar da Marquesa de Santos was listed as a historical monument of the State of São Paulo and incorporated into the municipal heritage.

After the restoration process was completed, the residence was reopened to the public on November 19, 2011,[2][3] and it is still possible to find some utensils, such as a bed, mirror, and a lounger used by the Marchioness.

[3] The Solar da Marquesa de Santos building is located near the Pátio do Colégio, the place where the city of São Paulo began and was founded.

Thus, the Solar da Marquesa de Santos is seen today as the oldest and main example of urban housing in São Paulo.

Even after undergoing many changes in its structure, many of the original features are still preserved, which brings to the house a great historical and cultural significance linked to the 18th century.

[7] Visitors to the Solar can find on-site furniture and household utensils that were used by the Marchioness de Santos herself, such as her bathtub, a piano, and portraits done by artists of the time.

[11] The restorations made in the manor were responsible for maintaining and bringing back characteristics that had been modified in the XIX century, such as the paneled ceilings, the floors, and the paintings.

[2] When visiting the manor, it is possible to find parts of the original walls, which were left exposed to inform what techniques were used to build the residence.

[2][3] Currently, the Solar da Marquesa de Santos is used as the headquarters of the Museum of the City of São Paulo and hosts several exhibitions.