In English, an adjective is usually placed on the left side of the noun it describes. But there are some exceptional phrasings here and there.

> 
> I had so great a time.
> 
> 
> 

The English present perfect tense probably evolved from being a statement about ownership.

> 
> I have a written book.
> 
> 
> 

could be rearranged to 

> 
> I have a book written. 
> 
> 
> 

and this slowly shifted focus away from "having" toward "writing" until it was eventually perceived to be a form of the verb "to write". As such the "written" would take the standard place in the verb cluster.

> 
> I have written a book.
> 
> 
> 

This looks very much like the (admittedly a little constructed) first example.

> 
> I had written a book.  
> 
>  I had so great a time.
> 
> 
> 

My questions are:

* Is the structure where an adjective come before the article of the noun a leftover from a time when English sentence structure was more flexible? If not, where does it come from?
* Is there any connection between the two sentence structures or is it just pure coincidence?