Our theories thus far are: speed control ( @ChapterAquila92 ) style / beautification ( @NIGHTBRINGER ) protection of coral reef ( @Lizards of Renown ) subterranean ballistic missile silo ( @Killer Angel )
I would like to add another theory: there is a "blue hole" in the middle of that (basically a sub-aquatic sinkhole) that they wanted to use to attract sight-seeing drivers.
A living legend has passed. One who saw the last World War, Churchill and (I believe) 14 Prime Ministers since him.
Truly a great women. Last night my brother pointed out that she was from the same birthyear as our grandmother (who sadly passed away four years ago) Something I did not yet knew. Grrr, Imrahil