DarthJ opened this issue on Dec 15, 2010 · 635 posts
DarthJ posted Fri, 04 November 2011 at 9:12 PM
2nd generation observation tower built in the 1970's. Because of stability problems these were replaced by square towers in the 1980's. The "11" refers to the number of rings which each were exactly 1 m high. Though confusingly enough sometimes the number also refers to the round type of towers ... even if they are not 11 rings high. While BT9 refers to the square type of towers ... even if they are not 9 blocks high. There is even a still existing BT11 with only 6 rings, which is sometimes being referred to as a BT6.
Can you still follow ?