Looking on the internet deeply has found these results:

This used to be a castle. is the most popular phrase on the web.

There used to be a castle here. 12,080 results on the web	This used to be a castle. 140,600 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Nearby there is a castle where I used to play as a child. Really, I can see that used to be a castle long time ago! Used to be the grand hall of a castle, until it sunk underground. Used to be the grand hall of a castle, until it sunk underground. There used to be a castle there. The grandiose announcement of a new Employment Pact turned out in reality to be a castle in the air. It doesn't even seem to be a castle. There used to be a really big house here.	I cannot imagine owning a castle. Nearby there is a castle where I used to play as a child. The grandiose announcement of a new Employment Pact turned out in reality to be a castle in the air. Really, I can see that used to be a castle long time ago! Used to be the grand hall of a castle, until it sunk underground. There used to be a castle there. Used to be the grand hall of a castle, until it sunk underground. It doesn't even seem to be a castle.

There used to be a castle here.

12,080 results on the web

This used to be a castle.

140,600 results on the web

More popular!

Nearby there is a castle where I used to play as a child.
Really, I can see that used to be a castle long time ago!
Used to be the grand hall of a castle, until it sunk underground.
Used to be the grand hall of a castle, until it sunk underground.
There used to be a castle there.
The grandiose announcement of a new Employment Pact turned out in reality to be a castle in the air.
It doesn't even seem to be a castle.
There used to be a really big house here.

I cannot imagine owning a castle.
Nearby there is a castle where I used to play as a child.
The grandiose announcement of a new Employment Pact turned out in reality to be a castle in the air.
Really, I can see that used to be a castle long time ago!
Used to be the grand hall of a castle, until it sunk underground.
There used to be a castle there.
Used to be the grand hall of a castle, until it sunk underground.
It doesn't even seem to be a castle.