Often dubbed the world's oddest capital, Astana is about to steal a bit of the international spotlight.

=As Astana is often dubbed the world's oddest capital, it is about to steal a bit of the international spotlight。

= Astana is often dubbed the world's oddest capital and it is about to steal a bit of the international spotlight。

参考译文：由于阿斯塔纳(哈萨克斯坦首都)被称作为世界最奇特首都，所以它正要打算窃取一点国际某体及公众的注意/关注。

以上为过去分词作状语用法，其逻辑主语为后面句子的主语，存在逻辑上主谓被动关系，所以用过去分词。

dub vt.给…起绰号;把…称作

(1)dub +宾语+名词=主语+be dubbed +宾语

The king dubbed him a knight.
国王封他为爵士。

We dubbed him Fatty because of his size.
因为他块头大,我们给他起了个绰号叫“胖子”。

London was dubbed “the insurance capital of the world”.
伦敦被称为“世界保险之都”。

The papers dubbed them The Fab Four'.
报刊给他们起了个绰号叫｀四绝＇.

At the height of her career, Orson Welles dubbed her 'the most exciting woman in the world'. 奥森·韦尔斯把处在事业巅峰的她戏称为“世上最令人兴奋的女人”。

(2)dub sb/sth as+名词

the man whom the Labour opposition dubbed as the 'no change Prime Minister'... 被工党反对派戏称为“不变首相”的男人.