It always amazed me how structures somehow got built over by other structures and sometimes even those structures got built over. Some ancient towns even have two or three layers or more, of buildings under their streets. I don't know about you, but I love that program on the History Channel that takes us beneath the streets of some ancient cities. It is amazing to see what is under there. I remember one show where they showed us streets from the middle ages that ran for quite a distance, that were buried under the streets of the city above. It seems that the people of the earlier era had sealed off a large area of their streets because the people there had the Black Plague and they wanted to keep them away from the rest of the population. I guess this must have been a death sentence. I don't think that I would have wanted to go down there even today, but that didn't stop the host of the show from entering some of the apartments down there. Yes the apartments and buildings still spanned that section of street and went up a couple of stories. It was all very weird.

Rome is an area that has much to offer in this respect. In certain places there are complete buildings that are under the streets of Rome and even older buildings under those. Along with the buildings you sometimes find sections of streets still in their original condition. It seems that building over this stuff helps to preserve them. Sometimes the condition of the buildings down there is incredibly good. It makes you feel like you stepped into some sort of time capsule. The construction of these Roman buildings was so sturdy that they put our modern structures to shame. Even the cement that was used was far stronger than what we use today. In some aspects of building, the Romans were ahead of us. Hey these were the people that invented the concrete that dries under water and we still haven't been able to make one as good, with all our labs and engineers working on the project. Isn't it amazing how we have to waste our time trying to rediscover something that was known in the ancient world for hundreds of years?

It is obvious that places where ancient buildings and streets are buried must have been at a lower elevation in ancient times. You never seem to hear of cities and towns going lower, only higher, with the exception of those places that are now underwater. It has to make you wonder how many of those ancient cities and towns are now off the coastline of different places. We know that there are certain structures off some of the islands of Japan and archaeologists have been arguing for years on whether they are man made or only seem that way. The problem is that they are sort of block structures and even though some divers claim to be able to see faces and such, some archaeologists argue that this is just a trick of our vision, which is interpreting lines and filling in the blanks a certain way. On the other hand, there are places off the coast of Greece and nearby islands that do definitely show the mark of man. Columns and statuary, vases and amphoras dot the underwater landscape. Sometimes the problem with this is that you can't always tell if this stuff came from a shipwreck, or an underground building or buildings, that have since disappeared.

This type of construction, the building upon other structures, seems to be universal. It does make me wonder why they did it in some circumstances. I say this because under certain circumstances it would have been easier to just build next to the original structure. I guess that sometimes certain areas that were connected with temples and such, might have been considered holy, so that is the reason for building above them on the same spot. This could be the reason for building several structures on top of the great pyramid in Mexico City. In January of this year an ancient Aztec pyramid was found right in the center of Mexico City. It turns out that Tlateloico's Grand Temple went through at least eight phases of construction over many hundreds of years.

Where is the most unlikely place to find buildings built on top of buildings? I have to say that I thought it was modern New York City, but I was wrong. It turns out some shops were built over and they can be seen abandoned, from certain subway lines. They are said to be in the same shape that they were in, in the early 1920s.

Are we going to leave structures that will be built over? In some areas of this country the builders have a head start. Let's look at Rochester, New York. At one time Rochester had a subway system. The system was no where as big and complex as that of New York City, but it did exist. As I am sure that you know, a subway system is already under ground, and is simple to build over in most cases. It is very interesting the way it was built. They rerouted the Erie Canal and used the abandoned canal as part of the subway system. The subway was constructed in 1919 and abandoned in 1956. It hadn't grown and was not useful for most people who had to travel to work. The subway is full of columns and other architecture and I am sure that some future people would think that they had hit pay dirt if they dug this thing up a couple of thousand years from now. It would be interesting to know if they could figure out what it was used for. If they do figure out what it was, will they be correct?

Usually when we find underground ruins, they are dug up and they go on display. China is putting a twist on this method. They are going to bury the ancient city of Liye in Hunan Province to protect it. In other words they are putting it back where it came from. Why are they doing this, would leaving the city exposed destroy it? This is a special case. The Chinese say that a nearby hydropower station that opened in 2003 is threatening the city's well being. When this city was dug up, over 36,000 bamboo slips were found. They documented different events of China's Warring States Period that ran from 475 to 221 B.C. Burying a city on purpose may have happened before, but this is the first time that I have ever heard of a city being reburied.

It is hard to imagine what else we might find underground. Since we know that many times buildings, cities and towns are built on top of each other, will we ever dig down to a point where we find something truly unexpected, maybe a civilization that was as advanced as we are? You never know what you might find.