Constitution Class

 

General description
The Constitution class was introduced around 2240. At that time the Constitution class was the fastest and most powerful ship type of the fleet and the only one officially designated as starship. 12 ships of this class were in service by the year 2267. Starting with the USS Enterprise in 2271, some Constitution class ships have undergone a complete reconstruction that included new warp nacelles, modification of the engineering hull and "neck", enlargement of the saucer section and a new bridge module. However, the ships were decommissioned at the end of the 23rd century, one of them is displayed in the Starfleet museum.
Known ships
USS Constitution NCC-1700
USS Constellation NCC-1017
USS Defiant NCC-1764
USS Eagle NCC-956 (refit)
USS Enterprise NCC-1701 (refit 2271)
USS Enterprise NCC-1701-A (refit 2286)
USS Excalibur NCC-1664
USS Exeter NCC-1672
USS Farragut NCC-1647
USS Hood NCC-1703
USS Intrepid NCC-1831
USS Lexington NCC-1709
USS Potemkin NCC-1657
USS Republic NCC-1371
USS Yorktown NCC-1717
Annotations
The Enterprise and Enterprise-A are the only reconstructed Constitution class ships that have been shown. It is supposed that the latter was first designated as USS Yorktown and later recommissioned as Enterprise 1701-A, so the actual number of ships is 14.
Class specifications
Heavy cruiser
Length: 289m (original), 305m (refit)
Deck count: 23
Crew complement: 430

Information source:
Bernd Schneider's Star Trek Website