Hoffman Mary Hoffman 
Stravaganza City of Ships [EPUB ebook] 

Set in Classe (Ravenna in our world), the Stravagante is Isabel, a younger twin by a matter of minutes. Her talisman is a pouch of silver mosaic tiles and she stravagates to Classe, where she is met by Flavia, a successful female merchant who trades spices, silks, tapestries, and whose son is an outcast and a pirate. Isabel finds that Classe and Bellezza are under threat from attack by the fierce Gate people. What can she do to help save the city? A thrilling story packed with action, pirates and drama.