The Philadelphia-class was a type of survey ship starship which was in service to the Federation Starfleet in the 23rd century. This class was named for the city of Philadelphia on Earth.

In 2269, the USS Billy Bishop, a Philadelphia-class vessel, was assigned to patrol the border of the Klingon Neutral Zone. (TOS video game: Judgment Rites)

Presumably, there would have been a USS Philadelphia prototype after which this class would have been named, a predecessor in the name to the later starships USS Philadelphia.

Starship classes of the United Federation of Planets
By name	Aakenn • Achernar • Achilles • Advance • Aegian • Aeolus • Aerie • Akira • Akula (destroyer) • Akula (frigate) • Alaska • Ambassador • Andes • Andromeda • Andor • Antares • Anton • Apache • Apollo • Archer • Ariel • Ascendant • Avenger • Babcock • Bader • Baker • Baton Rouge • Bode • Bolarus • Bonaventure • Bonhomme Richard • Bradbury • Brenton • Canada • Canopus • Capella • Centaur • Centaurus • Cerberus • Challenger (deep space explorer) • Challenger • Chandley • Charger • Chariot • Chesapeake • Cheyenne • Chimera • Christopher • Cle Dan • Cochise • Cochrane • Constellation • Constitution • Continent • Copernicus • Cygnus • Daedalus • Danube • Decatur • Decker • Defender • Defiant • Deneva • Derf • Dollond • Doppler • Dreadnought • Drexler • Durrett • Eagle • Edward • El Dorado • Enterprise (23rd century) • Enterprise (alternate future) • Epoch • Epsilon • Erewon • Excalibur • Excelsior • Federation • Fenlon • Fermi • Fiji • Freedom • Frontier • Gagarin • Galaxy • Galen • Geneva • Genser • Graceful • Grayson • Griffon • Hale • Hardin • Hephaestus • Hermes (scout) • Hermes (fast cruiser) • Heston • Hogan • Hokule'a • Horizon • Huron • Icarus • Incursion • Indomitable • Intrepid • Iowa • Istanbul • Iwo Jima • Class J • Karekh • Keith • Keppler • Kethkin • Kiev • K'Kmarak • Kolm-An • Korolev • Larson • Lauro • Laweya • Legacy • Lenthal • Lexington • Liberty • Loki • Loknar • London (troop transport) • Luna • Makin • Mann • Marklin • Marshall • M'Benga • Mediterranean • Merced • Mercury • Merian • Messier • Midway • Miranda • Mission • Missouri • Mockingbird • MoKal • Monoceros • Moscow • Mulciber • Nebula • Nelson • New Orleans • Newport • Niagara • Noble • Nomad • Northampton • Norway • Nova • Oberon • Oberth • Odin • Odysseus • Odyssey • Okinawa • Olympic • Oppenheimer • Orion • Osaka • Overfield • Paladin (destroyer) • Paladin (24th century) • Philadelphia • Phoenix • Pinnacle • Piper • Polarity • Pollux • Portsmith • Premonition • Prometheus • Proxima • Ptolemy • Pyrenees • Rakota • Ranger (cruiser) • Ranger (scout) • Reliant • Remora • Renaissance • Rickenbacker • Rigel • Rochester • Royal Sovereign • Saber • Sagan • Saladin • Samson • Santa Fe • Sawyer • Scorpio • Scylla • Sequoia • Shi'Kahr • Sierra • Siva • Solar • Sovereign • Soyuz • Springfield • Steamrunner • Surak • Sydney • Venture • Tangent • Theophrastus • Thomas Paine • Thucydides • Thufir • Ticonderoga • Tikopai • Tritium • Typhon • Ukora • Ulysses • Ural • Utah • Vesta • Vigilant (scout) • Vigilant (tactical escort) • Voyager • Wambundu • Wilkerson • Wei-Fa • Wellington • Wells • Yamato • Yorkshire • Zodiac • unnamed
By type	Federation cargo ship • Federation colony ship • Federation construction ship • Federation galaxy ship • Federation light cruiser (Intrepid-variant) • Federation mining freighter • Federation repair ship