What does the physical structure of the courthouse show about the people of Maycomb from To Kill a Mockingbird?

Scout describes Maycomb as being very old, and when she first describes the town she describes the courthouse. 

Maycomb was an old town, but it was a tired old town when I first knew it. In rainy weather the streets turned to red slop; grass grew on the sidewalks, the courthouse sagged in the square. Somehow, it was hotter then … (Ch. 1) 

This is a meaningful description.  It implies that the courthouse is tired out. The courthouse is old, and its ways are old.  It is not changing with the times, and it is not prepared for what it has to deal with. 

Scout describes how the courthouse is a product of a bygone era.  It had its heyday when Maycomb was a new town, full of promise. 

Because its primary reason for existence was government, Maycomb was spared the grubbiness that distinguished most Alabama towns its size. In the beginning its buildings were solid, its courthouse proud, its streets graciously wide.  Maycomb’s proportion of professional people ran high … (Ch. 13) 

By continuously bringing up Maycomb’s history and the history of the courthouse, Scout reminds the reader of the importance of heritage to Maycomb.  Tradition reigns.  Even when traditions are becoming quaint and outliving their usefulness, they hang on in Maycomb.  Racism will be a tradition that will be deep-set and hard to break with. 

A good example of this is the fact that the courthouse itself is basically the same one the town had in the beginning, even though it burnt down. 

The Maycomb County courthouse was faintly reminiscent of Arlington in one respect: the concrete pillars supporting its south roof were too heavy for their light burden. The pillars were all that remained standing when the original courthouse burned in 1856. Another courthouse was built around them. It is better to say, built in spite of them. (Ch. 16) 

Tradition is so important that the town just built a new courthouse around what was left of the old one, trying to maintain what it once had.  Nothing changes, even when things are forced to change.  It is important to honor origins.  Perhaps as a result, the courthouse itself seems to represent Maycomb’s identity crisis.  It is described as both Victorian and Greek revival.  The courthouse clashes with itself.

Thus, the physical nature of the courthouse mirrors what happens there.  During the trial, the town of Maycomb struggles with coming into a more enlightened and modern perspective, leaving racism behind.  However, it is a town so steeped in tradition that such a change would be very difficult, and is ultimately too much for Maycomb.  They get as far as getting a jury to deliberate, but they are not able to bring themselves to acquit the black man accused by a white man.