"Kal" or "Kaal" is the term used by Sephardic Jews to refer to the synagogue. The root comes from the word "Keila," meaning community. "The Kal" is the third book in the trilogy that started with "The Synagogue" and was followed by "The Synagogue."

In the book "The Kal," Elias Messinas continues the journey through space and time, with (spiritual) "companion" the late architect from Volos, Semtov Samuel, who, like the author, undertook a similar journey in the early 1960s. Elements from Samuel's archive, recently discovered, are published for the first time.

Through the pages of the book "The Kal," the dialogue, correspondence, notes in a notebook, and the search behind the research and documentation unfold. It is a journey in which the author, along with Samuel, captures a total of sixty years of living narrative about the synagogues and the people, the communities, and the architects associated with them.