During the American Civil War, was Washington D.C. actually the "most fortified city on earth"? | AskHistorians Archive Observer

During the American Civil War, was Washington D.C. actually the "most fortified city on earth"?

by OniAndy2

Also, did foreign observers comment on the city's defenses and whether they were unusually strong?

irrelevant_query

Follow up question, what would these fortifications look like? How large was DC's Garrison?