Short answers, pulled from the story.
In classical architecture, an attic is a storey or parapet positioned above the cornice of a classical facade. It sits at the topmost part of a building and was used for inscriptions, bas-relief sculpture, or as a full windowed storey.
The earliest known example is the monument of Thrasyllus in Athens. It established the attic as a feature of ancient Greek architecture and was seen as typifying the Attica style.
The attic above the entablature of St. Peter's Basilica measures 39 feet in height. It is one of the best-known large attics in classical architecture.
Attyka polska is the decorated attic with pinnacles associated with Late Renaissance Mannerist architecture in Poland. Examples can be found at Wawel Castle in Krakow, Gdansk, Poznan, Lublin, Tarnow, Zamosc, Sandomierz, and Kazimierz Dolny, with Krasiczyn Castle considered the finest example.
By the 17th century, the term entered common use through Attica style pilasters adorning the topmost facade. By the 18th century, the meaning shifted from the decorated outer wall to the interior space behind it, directly under the roof, producing the modern everyday sense of the word.
Palladio treated the attic as a complete storey pierced with windows in his work in Vicenza, making it functional interior space rather than purely decorative. The same approach appears at Greenwich Hospital in London.