We propose a diffusion-based approach for Text-to-Image (T2I) generation with interactive 3D layout control.Layout control has been widely studied to alleviate the shortcomings of T2I diffusion models in understanding objects' placement and relationships from text descriptions.Nevertheless, existing approaches for layout control are limited to 2D layouts, require the user to provide a static layout beforehand, and fail to preserve generated images under layout changes.This makes these approaches unsuitable for applications that require 3D object-wise control and iterative refinements, e.g., interior design and complex scene generation. To this end, we leverage the recent advancements in depth-conditioned T2I models and propose a novel approach for interactive 3D layout control.We replace the traditional 2D boxes used in layout control with 3D boxes.Furthermore, we revamp the T2I task as a multi-stage generation process, where at each stage, the user can insert, change, and move an object in 3D while preserving objects from earlier stages.We achieve this through a novel Dynamic Self-Attention (DSA) module and a consistent 3D object translation strategy.To evaluate our approach, we establish a benchmark and an evaluation protocol for interactive 3D layout control.Experiments show that our approach can generate complicated scenes based on 3D layouts, outperforming the standard depth-conditioned T2I methods by two-folds on object generation success rate.Moreover, it outperforms all methods in comparison on preserving objects under layout changes.Project Page: https://abdo-eldesokey.github.io/build-a-scene/