Two picturesquely-named photo editing tools, one free and one paid, allow you to digitally alter your photos to make intruders disappear. The GNU Image Manipulation Program or GIMP is the free-to-use software package; and the picturesquely-named SnapMania Tourist Remover is the paid one.
Both software packages work on the same theory - if you have a few pictures of the same scene, each one having intruders standing in different places blocking your view, these programs are able to take parts of the scene you want behind the gawking tourists in each shot from other shots, and stitch them together to make a seamless whole.
So how exactly does the whole process work? Either one of these two programs needs at least three shots of any given scene to work with. Each one of these shots needs to be taken out of the exact same position with no moving (preferably shot with a tripod). And each shot needs to have a different part covered or exposed. That's all the fodder that these programs need. With SnapMania, you load the pictures into the program and in a couple of minutes, it's managed to locate parts in each picture that are covered by passing people or cars and to fill them in with a section of the covered part taken from another picture. The effects can be magical. This can be a great digital photography tip. But sometimes, the effects can be comical.
Sometimes, the software doesn't manage to remove every vestige of every passing tourist. Sometimes you'll find just a disembodied head or just a disembodied foot still around in your picture. When that happens, you'll probably need to take more pictures of the scene to supply the software with. An easier option would be to get the program to process your pictures at a higher level of quality.
GIMP happens to be a kind of freeware version of Photoshop