The Delta house in Kifissia was built at the beginning of the 20th century to plans by an unknown architect.

In 1912 the building was sold by its first owner, the lawyer K. Lytsikas, to Emmanuel Benakis, the father of Penelope Delta, and two years later he transferred it to his daughter. The Delta family first moved into the house in 1916, after settling permanently in Athens. Penelope Delta lived in the house for 25 years, until her suicide in April 1941, on the day the German armies entered Athens. It was there that she wrote her best known stories, The Mangas, In the days of the Bulgarslayer, The Secrets of the Swamp, Crazy Antonis, and The Life of Christ, there that she kept her diary -parts of which have been published- with its important testimonies about her own life and the tumultuous contemporary history of Greece, and there that she carried on her correspondence about the contentious issue of education with individuals such as Yannis Psicharis, Kostis Palamas, Manolis Triantaphyllidis, and Demetris Glenos. In this house the Delta family frequently received leading politicians and intellectuals, and it was after spending the evening there on 6 July 1933 that Eleftherios Venizelos survived one of the attempts on his life.

The Delta house is a characteristic example of the mature neoclassical style of the early 20th century, with a number of eclectic features borrowed from medieval architecture, including the typically Athenian feature of a tower staircase. The interior is spare, with wood panelling, but without the plaster-of-Paris ornamentation common to bourgeois houses of the period. The Delta family built an addition at the south-west corner of the house in ordrer to enlarge the author’s work space and they installed an external elevator. These alterations do not affect the character or the morphology of the original building.

The restoration of the building began in 1992 according to the architectural study by G. Plessas and A. Zannas.

Since 1994, the Historical Archives Department has been rehoused in Delta house.