Final answer:
Corrie ten Boom is most surprised by the presence of hidden compartments in the construction of the secret room in 'The Hiding Place.' This detail demonstrates the ingenuity required to hide Jewish people during the Nazi occupation.
Step-by-step explanation:
In "The Hiding Place," the detail of the construction of the secret room that most surprises Corrie ten Boom is The presence of hidden compartments. Corrie is taken aback by how the builders were able to create a concealed area within her own familiar surroundings that is virtually undetectable, demonstrating the ingenuity and craftsmanship involved in keeping it hidden. In the context of World War II, such secret compartments were typically used for hiding Jewish people from the Nazi regime. The construction of the secret room in her family's house, which was used to hide Jews during the Nazi occupation of the Netherlands, involved great risk and innovation.
The secret room's creation required a reconfiguration of existing space, and finding a location that wouldn't raise suspicion. It needed to be accessible yet hidden, and the hidden compartments added to the effectiveness of the concealment. As a watchmaker's home, the Ten Boom house was not an obvious place to include such secret spaces. The building of the secret room showed the remarkable lengths people went to protect others, a theme central to the story.