I have updated my comment below with pictures. Take a look :)

While we’re reviewing different proposals and it will take time, we’d love to know what kind of stamps our users care about most:

There could be one set for the 7 Wanders of the Ancient World and one set for the New 7 Wonders of the WorldWonders

Here are some more details about this great idea:

The 7 Wonders of the Ancient World are:

Images Source: National Geographic