Some interesting to explore maps?

After watching THIS I was thinking : " Are there any maps which are interesting to explore , find secrets or maybe even some plot ? "
Are there any?

Plenty.

gm_atomic has some secrets, but is amazingly shallow.

rp_cscdesert is a great mix of storyline and secrets.

sb_sunken has everything underwater. There is some story there, and plenty of exploration space.

gm_apocalypse:
http://www.facepunch.com/showthread.php?t=993307

City 8 maps:
http://www.facepunch.com/showthread.php?t=875103
(Links to the other two are in the OP)