We report on our software development experiences within a large industrial company, and present technical debt in the form of architectural anti-patterns observed first-hand in our roles as developers and architects. Moreover, we identify and discuss socio-technical root causes of this technical debt. Our main contribution is six lessons learned, one for each root cause, and a division of these lessons into two categories, teamlevel and company-level, with different characteristics. We argue that as developers and architects, we can mitigate the team-level root causes. On the other hand, the company-level root causes must be resolved at higher organizational levels. As software professionals we can only try to increase awareness about them. In everyday software development, company-level root causes should be acknowledged as given circumstances that must be accepted and managed, recognizing that their resolution requires a long-term effort and action from senior management.