Dealing with ageing software is a reality of the industry, and even open-source software systems. This is a great opportunity for the software engineering researchers to apply the traditional techniques of program analysis to solve problems of refactoring and modernization. The generative AI advancements have opened up a whole new world of possibilities for software engineering tasks such as code generation, code translation, bug fixing among others. Industry is keen on exploring scalable solutions for refactoring, automated testing and now automatic code generation.

In this tutorial, we aim to (i) provide a background and overview of legacy software modernization and its importance amidst the emergence of AI-Assisted software and Generative AI (ii) discuss the challenges being faced by industry due to monolithic legacy code and systems (iii) introduce architectural and technological paradigms to modernize this legacy or ageing software (iv) highlight the research and engineering problems that remain to be solved in this space discussing the opportunities for the software engineering research community.