VERIFIED SOLUTION i

How to add Gridlines in 64-bit versions of MapInfo Pro

Products Affected: MapInfo Pro™, MapInfo Pro Advanced, MapInfo Discover 2015.2 and 2016
 
In MapInfo Pro™ v15.2, the Gridline tool appears under tab Map > Options > Gridlines

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MapInfo Pro v16.0 onwards, the tool has been placed more logically under Map> Content.
Click on Add to Map drop down to see Gridline option
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UPDATED:  July 5, 2017