Recently renovated, this Cathedral of St Jean in Lyon France looks fantastic inside and out. This cathedral does allow you to use Tripods so it was a blast setting up the shot and taking my time to compose. Although this place is very busy with tourist, so taking a shot like this becomes difficult. The best way to achieve a clean shot is to shoot at ISO 100 or 200, what ever is the lowest on the camera. You do need a tripod for it because using such a low ISO means your shutter speed may be 1 second or 5 second or more.
Take the shot when you find people are moving around and now standing still. This means that if they are moving at the instance you take a photo, they will most likely become invisible. However, make sure you take a few shots at the same spot when people are around different positions in your compositions. What this allows you to do is to take the photo and layer it up in photoshop and then reveal only the clean areas where there are no people.
In the next few days, I will publish a post that shares more details on how to achieve this.