Hope I have understand your meaning correctly.
If you can make a page that is only single column (since I forget can we choose one column in one page, sorry about that).
Assume it can be done, then you create a page with just one column and edit it to have a big map.
Making use of the menu, to make it be the first page for the users.
And in the map, it will have link to other pages which is originally with two columns as default.
Then you can have a view like that.
Hope this can help you.