Just thought you guys might be interested in this pic.
Cork City (Ireland) has a large network of tidal waterways in Culverts (large pipes basically) under the city. The city was originally on a network of small islands and during the 18th and 19th centuries they basically filled in and created culverts in the spaces between these islands creating main streets.

So, all of our main streets have at least 1, if not 2 or 3 of these channels running under them. They are not sewers and generally do not even connect to the surface water drains (there's a major risk of flooding if they're open as they can fill dramatically at high tide)

You can also see some exposed ducting under the street. Looks messy, but the older ducts you see crossing the culvert are pretty ancient.



Some of the culverts were opened and exposed (and inspected) during the city's recent complete replacement of drainage and sewage systems. The project went on from 1998 to 2005 (various streets closed to traffic for months at a time). The city's sewage system was centuries old and starting to become a major problem - collapsed pipes etc leaking their contents into the culvert system and into the river/harbour.

The various services : electricity, gas, water, telecommunications etc were all upgraded and replaced while they had the streets open and the city was given a full repave job.

The drainage aspect cost about €250m (about $336m)
Repave and replacement of services was quite a bit on top too. Pricey enough in a City of about 250,000 people. Well worth it though as the water quality in the river (and harbour) is now back to a level where it's even safe enough to swim in once more.

There's now a whole photographic archive, shows everything from viking house remains to victorian electrical systems.

Interesting browse!

http://www.corkpastandpresent.ie

It's amazing just what lurks beneath city streets throughout the world. I'm convinced that there are as many holes under London as there is solid ground!

I was reading a DIY paper the other day about garden underground water/heating/etc systems, an was wondering, how many of these people draw a plan of their houses. This can be dangerous if you sell the house, and the new owner has no idea where is the clean and the used water is coming from, and where not to dig in the garden...

I think Cork did a great dis-service covering those "Canals."

I can picture it now ... American tourists, bundled in wool, being rowed through the icy Irish mist, serenaded by "Danny Boy" ......

You can go to Christchurch NZ, and do the same on river Avon. I guess there must be a similar river in the US too...

I don't know if watching the History Channel's Cities of the Underworld counts as research, but: It appears with multiple European cities that, at some point, these waterways became open sewers as the population grew. Not surprisingly, folks clamored for them to be put out of sight, out of smell. Later, cities developed true sanitation and sewer systems, and are now finding that some of these waters are becoming clean again.

As a kid I heard a story of all the empty rooms and strange tunnels under Stockholm. I've been a bit curious ever since. It's said it looks like a swiss cheese underneath. Lot's of old things, sewers, unfinished subway tunnels, pumping stations, cable tunnels, and old reactor hall (!) and what not. I heard they have recently replaced the oldest gas pipes, laid in the 1850's. IIRC it was a company from London that built the first gas distribution system in Stockholm.

A place I lived in Cornwall in the 1980s actually had a small stream running under the property (and under several neighboring places).

When an extension was built on the back at some time in the past, it just had a raised floor level to straddle the stream.

I'd always been fascinated by 'what lies underneath the ground' and at about the age of 13 I dug a huge pit in our garden, in the floor of our old Anderson, eventually arriving at a bed of gravel lying some 8 feet down. The following day I discovered there was a lot of clear water flowing across my pit; I'd struck an amazing underground river! This epic news was not well received by Ma, - who stored her garden tools there - so it was promptly filled in again.

Then there is the Catacombs of Paris.
New York has quite an underground, but at least it has that shist bedrock it is built on.

We even have part of the old Edinburgh undergound that you can go and visit.

Mary Kings Close

It even has ghosts (if you belive in such things)

LOL,
There's always someone around to spoil the fun.

I too am pretty fascinated by the mysteries that lie underfoot. Here's a pretty cool website that has lots of information on subterranean facilities and whatnot, both military and civillian.

http://www.subbrit.org.uk/

There are lots of pictures and information about various underground and other interesting sites, in the UK and some in Europe. They also sometimes have special events for members, to tour some sites. I've been looking to see if there is a similar organization here in the US, but haven't found one yet.