What made me excited was my being taken to the Great wall.这里

这叫动名词的被动
was 后面要跟名词,因此,原来的take 要变成动名词taking
然后第二步,这个take 又要表被动,因此是动名词的被动,being done
第三,由于being done 这个动名词的被动仍然是名词性质,因此,前面用物主代词修饰,用my
因此,整个就是my being taken