Lord Valentine's Castle

From Author Wars - https://authorwars.com/publications/lord-valentines-castle-208957.html

Overview:

Title: Lord Valentine's Castle
Author: Robert Silverberg
Year: Unknown
ISBN-10: 0553144286
Publisher: Bantam Books
Price: $2.95
Pages: 447
Binding: Paperback
Type: Novel
Title Reference: Lord Valentine's Castle
Notes:
3rd printing (per number line) of 1981 Bantam ed.
Cover artist is uncredited and signature is not visible on cover, but the juggler is the US image painted for this title by Jim Burns.
There are five maps at the front of the book, all are uncredited.