1. The Tour Odeon Monaco in Monaco is rumored to be the most expensive tower in the world, with average unit sales of $8,000 per square foot and a $350 million penthouse. 2. Charleston, South Carolina is a historic coastal city that is growing in popularity for its lovely weather and growing tech industry, making it one of the fastest growing cities for software in the US. 3. On the Hawaiian island of Kauai, the luxury community of Kukui'ula has home sites starting at $1 million and cottages selling for $2.5 million, located around the central Plantation House.