LibreOffice: cleaning and re-factoring a giant code-base or why re-writing it would be even worse. A series of stories about how we've tackled the huge challenges of updating an old code-base and giving it a bright future and the impact of large-scale code-change in that process on quality and features in 4.0. Come and hear how we've built an international team of developers to tackle the problems of resurrecting a poorly-understood, gigantic code-base extensively commented in German, with no unit tests, a tangled build infrastructure, and twenty-five years of un-paid technical debt. Hear some stories of where we've come from - some comedy architectural disasters, and where we want to move to. Find out how you can get involved in that process. See the bug metrics, how we track our progress, regression counts, and the tooling we use to encourage participation and adapt the code. Does paying technical debt by significant, risky re-factoring pay? come and see the bug metrics. See how we've innovated on top of this base with new features, new platforms and hear about some of the goodness in LibreOffice 4.0.