How to build systems that age well? (System Architecture and Design Principles)

What are the principles you need to follow to ensure these systems don't become "legacy" that no one wants to work on? How to ensure adding new functionality doesn't make thing worse? How to select your technology? What architecture should you follow?

This session will cover the principles to follow that leads to building software systems that can grow whilst meeting the business and customer needs and still being efficient and enjoyable to work on.