If you draw a line straight west from Baltimore and another line straight northwest from Washington, Frederick is where the two meet.
It was settled in 1725 and incorporated in 1817. At one point in the 19th Century it was the 49th largest city in the United States (today that would be metro areas comparable to Albany, Birmingham and Richmond).
Frederick has a marvelous center city. The downside is it is very rapidly becoming a less expensive alternative for people priced out of suburban Washington, and therefore has a rapidly expanding sprawl belt.
You can get more info and see more pictures at my
Frederick profile at BeyondDC.