As announced this past weekend, Wikidata is now 5 years old, congrats! [1] 

In that announcement I discovered something I hadn't know about before — that you can now add a small script to your account's common.js file on Wikidata.org to add a map to items that have coordinates. W00t!

It was created by User:Aude and it adds an interactive map when you look at items that have coordinates. It's simple to use, just log into (or create an account) on wikidata.org, surf to your common.js and add in this detailed script. [3] I created a snapshot of what it looks like and uploaded it to Commons. [4]

There is another similar script that User:Mxn created that is very similar but uses Overpass to generate the map. [5] 

Enjoy using maps in Wikidata!