Tango Tek built this not me I just re-created it as I couldn't find a schematic and don't want to wait for world download. I will be building all parts soon.
Video I followed is - The Ice Fortress Rises! - Hermitcraft 9: #17
In the first part the top of the tower was not big enough for the second bit but it is fixed in this one.
I am hoping to finish the front gate and outer 4 towers this week so stay tuned!
Enjoy!
CREATIONS
MINECRAFT-SCHEMATICS.COM