The first-floor Senate corridors designed by Constantino Brumidi are elaborately decorated from floor to ceiling. Although many artists contributed to their painting, they are often called the Brumidi Corridors. Because the corridors are a high-traffic area, their corners and walls are constantly being damaged and repainted; in fact, this process began soon after they were finished, and they may have been first repaired by Brumidi himself in 1861. Over the years, the varnish applied to protect the walls significantly yellowed with time and the background fields have been repainted without being cleaned to match the yellowed varnish and grime, obscuring the original colors and many of the beautiful details. The decorations originally described as predominantly red, white, and blue became yellow, tan, and murky green. In the twentieth century, even Brumidi's historical frescoed scenes were painted over when damaged or darkened with grime. Over the past quarter of a century, professional conservators trained in fresco conservation in Italy have removed layers of overpaint and uncovered the original designs and colors of Brumidi's frescoes and murals. (More information about the design and history of the Brumidi Corridors and a summary of conservation work since 1985 are available.)

The long-range planning for the conservation of Constantino Brumidi's historic murals in the Capitol began in 1981 with a survey and identification of priorities by a respected conservator. His report has since been updated by inspections and studies, including a major technical survey and analysis completed in 2002. Funds for the conservation of wall paintings have been regularly appropriated since 1985, allowing one or more of the areas with murals by Brumidi to be cleaned and conserved each year. After all of Brumidi's lunettes (the semi-circular areas over doorways) painted in true fresco in the first-floor Senate corridors were conserved, a long-range plan to restore the decorative painting on the walls was launched in 1996.

In 1985 conservation work was carried out on the John Fitch frescoed lunette in the Patent Corridor and on twenty-four medallions of landscapes and animals in the Senate corridors. The years from 1986 to 1988 were devoted to the conservation of Brumidi's frieze and canopy in the Rotunda and his first frescoes in the Capitol, which are located in room H-144. In the corridors, the bronze railings of the Members' staircases designed by Brumidi were cleaned and their original patina was uncovered in 1987 and 1988. In 1989, the conservation of the frescoed lunettes in the corridor resumed with the damaged Benjamin Franklin and Treaty of Peace. In 1991, three heavily overpainted frescoed lunettes by Brumidi, Columbus and the Indian Maiden, Authority Consults the Written Law, and Robert Fulton, were conserved. In 1992, the lunette Bartholomé de Las Casas, unusual for having been painted in oil, was cleaned of extensive overpaint; Bellona and the Cession of Louisiana were also conserved that year. This conservation work was carried out by a number of conservators qualified by their study of and experience with frescoes in Italy, including Bernard Rabin, Constance Silver, Catherine Myers, and Christiana Cunningham-Adams. Cunningham-Adams Fine Art Painting Conservation has successfully competed for the contracts for all of the phases of the specialized work on the walls.

Although no funds for the conservation of wall painting were appropriated for fiscal years 1992 or 1993, no-year funds appropriated in 1990 for the conservation of the north entry were carefully allocated to attain the maximum benefit. The three frescoed portraits of Justice Joseph Story, Chancellor James Kent, and Chancellor Robert R. Livingston by Brumidi in the north entry were cleaned and conserved in 1992. This work was followed by more extensive research, testing, and analysis of the murals in the complex first-floor corridor area to determine the original designs, colors, and techniques on the walls and ceilings. These studies determined that all of the ceilings were originally painted in tempera (pigment mixed with glue or other binders) and that the walls were painted using a variety of paint mediums, including a form of fresco.

The phasing of the conservation of the walls of the Brumidi Corridors was based on the detailed study and resulting 1993 report by Cunningham-Adams Fine Art Painting Conservation. The report outlined a ten-year plan for restoring the corridors. Beginning in the area called the Patent Corridor, conservators have removed overpaint from the birds, animals, flowers, and classical motifs to restore the original designs painted under Brumidi's direction. Where the plaster has become detached, consolidants are injected into the cavities. In order to saturate powdery plaster with the consolidant, a system of hanging bottles and tubes controlled with valves was developed to introduce the specially formulated consolidant and a slow and steady rate. This consolidation is necessary to allow the conservators to safely remove the overpaint. Missing details and areas are reconstructed using reversible paints. The trompe l'oeil moldings around the panels were discovered to be mostly intact and are uncovered. The plain borders, formerly a murky green, are repainted to their original sandstone color; the use of electronic instrumentation allowed accurate matching of the original colors. The last step is to replicate the shadows around the panels and the illusionistic moldings on the pilasters.

After the walls in the Patent Corridor were restored to their original beauty, the conservation has moved phase by phase in the North Corridor. Phase IX is essentially completed and Phase X is now under way in the West Corridor. Over time, the conservators have discovered a variety of paints and a variety of problems in different sections of the corridor. Some panels lay in almost perfect condition under the overpaint, while others were severely damaged and had been replastered, with no original to be found.

Stanchions have been installed to help protect the conserved murals from damage, and exhibits have been installed to explain the history of the murals and the conservation work.