The cardiac conduction system (CCS) is responsible for the initiation and propagation of the action potential through the heart and it consists of the sinus node (SN), right and left inferior nodal extensions (INEs), atrioventricular node (AVN)/penetrating bundle (PB), His bundle, right and left bundle branches, and the terminal Purkinje fibres (PFs). Atrioventricular ring tissue (AVRT) is made up of nodal-like myocytes and consists of the right ring (RR), left ring (LR), aortic ring and the retroaortic node (RAN). Unlike the CCS, the AVRT is not involved in the normal initiation and propagation of the action potential through the heart, but it can be responsible for atrial tachycardias. The aim of this study was to determine the full extent of the CCS and AVRT and to make a 3D anatomical model. Six Wistar-Hannover rats (3 months old) were euthanized by cervical dislocation in accordance with the United Kingdom Animals (Scientific Procedures) Act, 1986 and the hearts were harvested. One heart was fixed and subject to magnetic resonance (MR) imaging. The remaining hearts were frozen and cryosectioned in the long axis from the posterior/back to anterior/front. Every 100 μm, tissue sections (25 μm in thickness) were stained with Masson’s trichrome and immunolabelled for HCN4 and Cx40 (markers of the CCS and AVRT), Cx43 (marker of the working myocardium) and caveolin3 (marker of cardiac myocytes) to identify the tissues of the CCS and AVRT. The anatomical location of all components of the CCS and AVRT and their posterior-anterior extent were similar in all hearts. The posterior-anterior extent for all structures mentioned above was: SN ~2.3 mm, INEs ~0.4 mm, AVN/PB ~0.7 mm, His bundle ~2.3 mm; RAN ~0.5 mm; RR ~1.8 mm; LR ~1.3 mm and PFs ~6 mm. In the sections, the PFs tended to be located more anteriorly and they terminated mainly at the apex of the left and right ventricles. The histology and immunolabelling were used to segment the tissues of the CCS and AVRT in the MR images of the first heart. Finally, using Matlab, a 3D anatomical model of the heart with the CCS and AVRT was constructed. The 3D model shows that the AVRT is discrete from the CCS and yet is continuous with it: beginning from the right and left INEs, the AVRT tissue extends around the tricuspid and mitral valves (to form the RR and LR) and unites in the RAN. Our model provides an anatomical reconstruction of the whole CCS and AVRT and, therefore, is a useful tool for teaching and research purposes.