<p>Tour guiding plays a key role in turning sightseeing into memorable experiences. Tour guides, especially inexperienced ones, must practice extensively to reach proficiency. Skill-sets typically include knowledge about sights, in-situ presentation, and a convincing ability to interact with and engage tourists. These skills require on-site training with live tourists. However, with modest budgets, such setups may be out of reach and trainees have to compromise with off-site or simulated classroom setups. To tackle this problem, we present the development and evaluation of VRGuideMaster; a VR system enabling its users to practice tour guiding with 360-degree travel videos. With VRGuideMaster, a tour-guide trainee equipped with a HMD can rehearse presenting while immersed in a virtual environment constructed from 360-degree tourist site videos. Additionally, in the virtual environment, the trainee can communicate and interact with video streams of tourists, who remotely join in through their mobile and personal devices. The result of a user study (n = 12) comparing VRGuideMaster with a baseline emulating the practice of showing 360-degree videos via conventional video conferencing interfaces, shows that overall, VRGuideMaster was more effective in supporting tour-guide trainees in practicing their tour-guiding skills.</p>