Why were whispering galleries built? and what are their sizes?
A whispering gallery is usually constructed in the form of an ellipsoid, with an accessible point at each focus. When a visitor stands at one focus and whispers, the line of sound emanating from this focus reflects directly to the dish/focus at the other end of the room, and to the other person. Circular whispering galleries may provide "communication" from any part on the circumference to the diametrically-opposite point on the circumference.
The plural of gallery is galleries. The plural possessive would be galleries'.
Art galleries and museums.
Whispering Jack was created in 2006.
Whispering Wind was created in 2001.
The Whispering Vault happened in 1993.
Whispering Sands was created in 2001.
Whispering Your Name was created in 1994.
Whispering to Witches was created in 2004.
The Whispering Statue was created in 1937.
The Whispering Shadow was created in 1933.
Whispering to the Shadows was created in 2002.