Starbase 718

From Memory Alpha, the free Star Trek reference.

Starbase 718 is a Starfleet outpost located near the Romulan Neutral Zone. In 2364, Captain Jean-Luc Picard attended a conference there. (TNG: "The Neutral Zone")

According to the Star Trek Encyclopedia, after "The Neutral Zone" aired, it was decided that the number of starbases would be kept low (i.e. under 500). The only other starbases whose numbers are higher than 500 are Starbase 514, Starbase 515 and Starbase 621.