Phil in SF quoted Haunting of Tram Car 015 by P. Djèlí Clark
Cairo, 1912: The case started as a simple one for the Ministry of Alchemy, Enchantments …
A sprawling vintage Anatolian rug of blue angular motifs, red spandrels, and golden tulips bordered in deep lavender.
— Haunting of Tram Car 015 by P. Djèlí Clark (Page 10)
First page, and already a new vocabulary word: spandrel.
The almost triangular space between one side of the outer curve of an arch, a wall, and the ceiling or framework.