The best you can do is to click the "Places" in the sidebar, while in Photos view. This screenshot is from Photos 3.0 in High Sierra macOS 10.13.2
It is not possible to show a trip half around the world on one map any longer. If we zoom out as far as possible, we can see roughly a quarter of the earth. I have sent feedback to Apple about this problem several times, because the missing world map it is taking the fun out of the maps feature, if we cannot show all places of one long distance trip on one map. This has been the case since Photos 1.0, and it started with Aperture 3.5.1 and iPhoto 9.5.1, when apple stopped to use Google's map servers. Since then, the maps do no longer show terrain data, and can no longer be expanded to show the whole earth.
It is slightly better in Photos 3.0. In Satellite View we can show half the globe, but still no world map. And if we zoom out to show the globe, the photos will be collapsed in large stacks, so that many places are missing.
The thumbnails on the maps are occluding all details, and worse, we cannot choose the thumbnails. Photos does not even pick them from out favorites, but seems to prefer photos with people in them. On the map I would want to see my favorite photos of the landmarks, not some stranger talking a selfie in front of the landmark. I vastly preferred the pins on the map, that let us see the places labels.
Please send also feedback. Even if the feedback forms are only available in English, they will be read, if you fill them out in German. Apple - Photos - Feedback