Examining the structure of old buildings

Question

Generally speaking, many cities were built across long periods of time. When a city is expanded, still in general, the old part becomes the center, and the new parts increase the size of the city from the center to the peripheral zones.

In those cases, one can examine the design of the city and deduce the city was built in different phases, and not in one single building operation (at least I guess), from the placement of the central buildings or for some remaining pieces of walls, or something else.

Now, my question is: can an expert do that also for a single building? And how?

For example, examining a huge structure (I'm not in the field, I just hope the examples have sense), for example a museum or an hospital (not considering a close group of buildings but a single big one), how can some expert deduce a wing has been built in a later stage due to some successive necessities?

In the example above, if the museum needs to accommodate more and more stuff, they could decide to build some additional structure, attached to the already present one, and connect them with some doors. In this case, is it possible discern what was built before and what after? And how is it done?

This, in reference generally to old or ancient buildings, because I do not know if they do that even today.

Also, I am interested to know if this can be reasoned NOT considering different materials, architectural styles or techniques, but ONLY from the placement, shape and size of the different parts (for example, symmetries, access paths or other pure geometrical concepts).

That is, what I'm primarily searching for is the thought process of someone with just a visual inspection of the structure (if the structure has been coated and painted inside and outside, excluding the exam of the bricks or other materials and also excluding non invasive ways like x-rays of the walls - if they do that).

Answer 1

Your question specifically asks for a deduction. There's an important distinction between deduction and inference. Probably there isn't enough info from a walk-through to make a conclusive deduction as to the date of construction of parts of a building. But it is possible to infer an opinion. Inference goes beyond the facts, observations and reasoned deductions and makes what is essentially an educated guess. The more expertise, the more knowledge of local construction history, building materials, etc the better the educated guess, or inference.

By far the best source of information are people familiar with the construction history of the building itself. Former owners, occupants, and municipal building permit archives may provide specific information that will allow more concrete deductions.

Parts of my home are over 130 years old. I know that because I've seen old pictures with the date written on them – deduction. I've observed during renovations that parts of the building were probably built at different times because of the changes in building materials from one part to the next. The use of the word "probably" means inference – an educated guess. I was also able to use geometry information. It looks like what was once the front porch was eventually enclosed, as I found parts of the porch railing inside the wall when I removed a section of drywall.

For a more specific answer, I would update the question to include specific information about the building in question, whether it's the pyramids in Egypt or an old country barn.