Google maps

Finding markers is a real problem. It also involves turning optimisations off, which has a huge performance penalty, so that only works in test environments.

http://tech.adstruc.com/post/34230170061/selenium-testing-google-maps

https://groups.google.com/forum/#!topic/google-maps-js-api-v3/FEvhvZrZ4fg

What you can do though, is if you know a marker should be present is find the marker in the source code:

command: verifyHTMLSource
Target: *markernamestring*

The * is necessary because there are other characters touching the name of the marker.