Placing a Fortress via a event?!

[Colwyn]

What events text will I need to place a Fortress at say map location 64,126

Below is a example of how to change terrain from water to say plains, I am hoping all I need is the terrain type number from someone for a fortress! or do I need to do something else.

@IF
TURN
turn=20
@THEN
TEXT
^The Don river freezes in the harsh Russian winter and the pack ice crushes
the German pontoon bridge erected near Stalingrad last summer.
ENDTEXT
CHANGETERRAIN
terraintype=1
maprect
65,129,65,129,65,129,65,129
@ENDIF

@IF
TURN
turn=20
@THEN
CHANGETERRAIN
terraintype=10
maprect
65,129,65,129,65,129,65,129
@ENDIF

[Mercator]

It's not possible. CHANGETERRAIN can only change to 1 of the 11 terraintypes.
The other possibility would be to make a strong immovable unit and put that on the place you want with the CREATEUNIT event.

[Colwyn]

Thank you

Thanks!