Does anyone know what these are called?

[J Route Z]

http://goo.gl/maps/6Eqvj

closer view: http://goo.gl/maps/IrtlD

There are tons in Philadelphia.

[Roadrunner75]

http://goo.gl/maps/6Eqvj

closer view: http://goo.gl/maps/IrtlD

There are tons in Philadelphia.

Gasometer or Gas Holder:
http://en.wikipedia.org/wiki/Gas_holder

[DeaconG]

http://goo.gl/maps/6Eqvj

closer view: http://goo.gl/maps/IrtlD

There are tons in Philadelphia.

Gasometer or Gas Holder:
http://en.wikipedia.org/wiki/Gas_holder

Haven't seen those in years, as a child I was fascinated as to how a tank could be full...or not full...and how the hell did that happen?