Why did it take so long to find the greater city of Troy?

I like the question stated in the title of this entry. But I cannot answer it. 

Why did it take until now to find the huge buried city of Troy?  The citadel's location was fixed in 1822 by Maclaren. Calvert began excavating there some years before he met Schliemann.  Schliemann excavated and publicized the site starting in 1871.  It has been 150 years since Schliemann's arrival at Hissarlik, and 199 years since Maclaren's dissertation. 

My only working thought on this is that there must have been very little, if any, effort expended on finding the lower city after Schliemann. Anyone who actually searched for it would have found it right where it was expected. That is why I believe that little was done to find it. A little effort would have changed history.  So, there must have been even less effort expended than would have been required.  

Curiously, there was a study of the stratigraphy of the plain of Troy.  The following graphic from Luwian Studies suggests that at least four holes were drilled in front of Hissarlik.   Those drill holes are represented in the top left insert, and again at the bottom left. 

During almost 150 years of research history in Troy, however, all excavations have been restricted to the hill of Hisarlık, which due to its elevation was never affected by mudflows. In other words, the actual lower city of Troy may indeed still lie hidden in the plain underneath a layer of gravel and alluvial silt. Approximately 300 drill holes that were made by Ilhan Kayan to investigate the plain’s stratigraphy produced thick layers with artifact-rich deposits. Accordingly, the buried lower city of Troy may already have been found in the floodplain. Archaeologists looking for the remains of the actual city of Troy may only need to dig a mere 5- to 6-meter trench 300 meters west of Hisarlık – and they are likely to make a breakthrough discovery surpassing that of Heinrich Schliemann. (https://luwianstudies.org/the-lower-town-of-troy/)

So, there has been some unintentional exploration of the tell at Troy.  How many holes went into the tell I do not know at this time.  I plan to look into it.  

During the Trojan War, the Greeks are likely to have destroyed levees and hydraulic installations. Since the war was fought in the dry summer months, their actions had no immediate effect. But when the winter came, with Troy already defeated and destroyed, the topographically low-lying ruins were buried under mud carried by the rivers. Thus, the remains of Troy are likely to be buried a few hundred meters west of Hisarlık, and remain hidden. Excavator Manfred Korfmann has said (in a personal conversation) that drill holes in the floodplain revealed pottery deep down below the present surface. The geoarchaeologist who investigated these deposits for almost forty years concluded, “some levels contain a great deal of archaeological material … Pieces of bricks, stones and mortar indicate the remains of a construction. … From an archaeological point of view, the area along the foot of the northern slope of Troia is an important one … In the light of these findings we consider that it would be very useful to make an archaeological excavation about 7 meters deep.”   (https://luwianstudies.org/the-history-of-troy/)

The Northern slope of Hissarlik?  I guess they were drilling in the Dumbreck valley as well as the Scamander valley.    

In 1819, when Philip Barker Webb arrived on Hisarlık, he watched the last remnants of the former city wall of Troy being carried away and said: “Future travelers will not even see the meager remains of it [the famous city] that a favorable fortune allowed us to meet.” Nevertheless, the city of Troy still exists and the ruins left after the destruction (of Troy VIIa) are potentially exceedingly well-preserved. If one draws a cross-section through the royal citadel on Hisarlık and extends it into the plain, it turns out that the remains of the lower town lie 5 to 7 meters below the surface of the modern floodplain. Stratified deposits full of artifacts, even entire building remains, have been identified in drill cores stretching several hundred meters apart. (https://luwianstudies.org/descriptions-of-ancient-troy/) 

The Luwian Studies site is not wrong about Troy or about its location or about the value of those drill cores from the stratigraphy study. The study not only discovered a few things about the age of the plain, it also discovered lots of artifacts.  Essentially, it did find the larger city. 

Now that we can see the tell at Troy, the findings of that study could be systematically compared with the tell to map out some of what is underneath the mud.