Ogaki is a small/mid-sized city located 10 minutes by train from Gifu-shi, the capital of Gifu Prefecture. The population of Ogaki (as of May 2012) is 164,000.
Trains run from Maibara in Shiga-ken (35 min away, 650 yen) and Nagoya (39 min away, 740 yen) along the JR lines.
Ogaki is a bit spread out, so it's advisable to have a bike or car available.
Ogaki Castle is the most well-known landmark in Ogaki, although it is a reconstruction.
Ogaki is famous for mizu-manju, a sweet, jelly-like snack that's filled with red bean paste. While it's primely served in the summer, it's available from late spring. You'll find it at a stall on the main road south of Ogaki station.
Gifu City is 10 minutes away by train (230 yen), and has about 400,000, making it the go-to "city" in Gifu prefecture.
Nagoya is definitely a good city-getaway if you feel suffocated by the ample countryside of Ogaki.