The B. Altman and Company Building is a commercial building in Midtown Manhattan in New York City, that formerly served as B. Altman and Company's flagship department store. It occupies an entire city block between Fifth Avenue, Madison Avenue, 34th Street, and 35th Street, directly opposite the Empire State Building, with a primary address of 355–371 Fifth Avenue.

The B. Altman and Company Building was designed by Trowbridge & Livingston in the Italian Renaissance Revival style. Most of the building is eight stories tall, though the Madison Avenue end rises to thirteen stories. It contains a facade made largely of French limestone, except at the Madison Avenue end, where the ninth through thirteenth stories and most of the Madison Avenue side are faced with white brick. The facade contains a large arcade with a colonnade at its two-story base.

Altman's was the first big department store to make the move from the Ladies' Mile shopping district to Fifth Avenue, which at the time was still primarily residential. The building was opened in stages between 1906 and 1914, due to the difficulty in acquiring real estate. The store closed in 1989 and was vacant until 1996, when it was renovated. The building was reconfigured to house the City University of New York's Graduate Center, the New York Public Library's Science, Industry and Business Library, and the Oxford University Press. The B. Altman and Company Building was made a New York City designated landmark in 1985.

The B. Altman and Company Building occupies a full city block in Midtown Manhattan, bounded by Fifth Avenue on the west, 34th Street on the south, Madison Avenue on the east, and 35th Street on the north. The building's land lot has a total area of 82,950 square feet (7,706 m²); it measures 197.5 feet (60.2 m) from north to south and 420 feet (130 m) from west to east. Because of the topography of the region, the northern ends of the Fifth and Madison Avenue facades are slightly higher than the southern ends.

The B. Altman Building is close to the Empire State Building to the southwest, 200 Madison Avenue to the north, the Church of the Incarnation to the northeast, the Collectors Club of New York to the east, and the Madison Belmont Building to the southeast. It is one of several former major retail buildings on the surrounding stretch of Fifth Avenue. Within four blocks to the north are the Gorham Building at 390 Fifth Avenue, the Tiffany and Company Building at 401 Fifth Avenue, the Stewart & Company Building at 404 Fifth Avenue, and the Lord & Taylor Building at 424 Fifth Avenue.

The B. Altman and Company Building was designed by Trowbridge & Livingston in the Italian Renaissance Revival style and opened in three phases in 1906, 1911, and 1914. The main section on Fifth Avenue, opened in 1906 and expanded in 1911, has its facade designed as an arcade. The Madison Avenue annex, completed in 1914, has more design motifs than the original Fifth Avenue structure and its addition. Marc Eidlitz & Son was the general contractor for the building, and Hecla Iron Works manufactured the metalwork.

The majority of the building is eight stories tall, but the Madison Avenue side rises to 13 stories. The original section of the building contained entrances on Fifth Avenue, 34th Street, and 35th Street, while the annex contained two additional entrances on Madison Avenue and 35th Street.

The structure's facade was generally intended to harmonize with the designs of mansions on Fifth Avenue, which at the time of the building's completion was largely residential. The design, across the street from the grand residence of department-store rival A. T. Stewart and diagonally across the avenue from the residence of Caroline Schermerhorn Astor, was planned to complement the surrounding palatial mansions. The design used imported French limestone. The B. Altman Building was the first commercial structure in New York City to use the material, which had previously been used only on residential buildings.