[1] The building contains the Esteban Echeverría Library, Salón Rosado (also known as the "Eva Perón Hall"), and a carillon which, when it was installed in 1930, was the largest in South America.

Approved and budgeted by the council in 1926, Ayerza's eclectic design drew heavily from French Neoclassical architecture.

The foundation stone was laid under the First Congress of Municipalities of the Republic of Argentina, on November 18, 1926, by Marcelo Torcuato de Alvear.

[2] Juan Perón, who established the Secretariat of Labor and Social Insurance, set aside a wing in the building for the purpose.

[2] It incorporates an older residence that faced the Plaza de Mayo but now fronts the Avenida Julio A. Roca.

The main door, located at the corner of Julio A. Roca Avenue and Peru St., is of carved wood with a central brass knocker shaped as a lion's head.

The Esteban Echeverría Library houses a unique collection of 2,000 books from the seventeenth to the nineteenth century.

The other library, known as the Hemeroteca José Hernández, has numerous newspaper archives from 1870 covering topics of history, culture and general news.

There are texts from Visigothic Spain, from the Viceroyalty of the Río de la Plata, and the colonial Buenos Aires Cabildo, and others.

The library was renamed to honor the Argentine poet Esteban Echeverria who introduced literary romanticism to the city.

After women obtained voting rights in 1947 and female politicians began to enter the government's legislative system, First Lady Eva Perón established the palace's Salon Rosado ("pink room"; now known as the Salon Eva Perón) as a reserved area for government women to discuss issues in a place from which men were excluded.

It houses some of the original furniture and personal objects such as a desk, chair, lamp, folders, ink and letter rack.