南阳武侯祠坐落于中国历史文化名城河南省南阳市区城西的卧龙岗上，坐西向东偏南，现存殿堂房舍267间，主要建筑由东而西排列在一条中轴线上，分前后两重，建筑布局严谨，疏密相宜，殿堂雄严，亭台壮观。
NowwearegoingtopayhomagetoZhangHeng,anoutstandingscientistandfamouswriterintheHanDynasty.
ZhangHengwasbornandburiedinNanyang.ZhangHeng'stombislocatedinShiqiaoTown,25kilometersnorthofNanyangcity.Itis8metershighand79meterslong.Itissurroundedbybrickpassagewaysandoctagonalwalls.Itissurroundedbygreenpinesandcypresses.Itisplantedalloverthegarden,coveredbygreengrass,andthecemeteryissolemnandquiet.ThefrontoftheflowerwallisthegateofJanuary.Therearetwotombstonesinfrontofthegate.OneiserectedintheJiajingperiodofMingDynasty,andtheotheriserectedintheGuangxuperiodofQingDynasty.ThereisastoneinscriptionwrittenbyGuoMoruoinfrontofthetomb:"suchapersonwithall-rounddevelopmentisalsorareinworldhistory.Itisadmirabletoworshiphimforthousandsofyears."
ZhangHeng,thewordPingzi,NanyangCountyWeste(today'sShiqiaoTown)people.HewasborninthethirdyearofemperorZhang'sreign(78)anddiedinthefourthyearofemperorYonghe(139).ZhangHengisintelligent,quickandeagertolearn,eruditeandversatile.Hehassetupatoweringmonumentinthehistoryofscienceandcultureintheworld,andisknownas"theworld'sculturalcelebrityandChina'sscienceleader."
LuoyangwasthecapitaloftheEasternHanDynasty.Atthattime,Luoyangwasthepolitical,economicandculturalcenterofthecountry.Scholarsgathered,schoolswerelikeaforest,academicatmospherewasstrong,andcultureandeducationwereunprecedentedlyprosperous.Inordertobroadenhishorizons,ZhangHengvisitedLuoyanginMarchofYangchuninthesixthyearofemperorYongyuan(1994).ThistimehelivedinLuoyangforsixyears.Duringthisperiod,hespenthismainenergyontravelingtoTaixue,visitingfamousteachers,seekingfriends,learningmodestlyandstudyingassiduously.
HewasproficientinFiveClassics(Yi,Shu,Shi,Li,Chunqiu)andSixArts(Li,Yue,she,Yu,Shu,Shu).WiththehelpofhisgoodfriendCuiyuan,hebegantostudyastronomy,mathematicsandcalendarinnaturalscience.HewrotealotofbeautifulFu,whichinitiallyshowedhisextraordinarytalentandattractedtheattentionofthesociety.Hehasahighattainmentsinliteratureandscience,whichlaidtheideologicalandtheoreticalfoundationforhimtobecomeagreatscientist.
InthelateautumnofA.D.100,BaodewastransferredtoNanyangPrefecture.RecommendedbyCuiyuan,23-year-oldZhangHengleftLuoyang,thecapital,andwentwithBaoDetoNanyangPrefectureasthegovernor.
InthefifthyearofEmperorHanan'sYongchuperiod(111),BaodeandothersplayedontheMingemperorinBeijing,whichmadeemperoranknowthatZhangHengwasknowledgeable,sohetookthebustoNanyangtoenlistZhangHengtobecomeadoctorofShangshutaiinLuoyang.Threeyearslater,hewaspromotedtobeshangshilang,andthenextyearhewaschangedtoTaishiling.
Taishilingwasinchargeofastronomy,calendar,meteorologyandsacrificialceremonies.ThiscreatedaveryfavorableconditionforZhangHeng'sin-depthstudyandpracticeofastronomicalcalendar.In133,ZhangHengwaspromotedtoserveasasenioradvisortotheemperor.InthefirstyearofYonghe(136),EmperorShunofHanDynasty,ZhangHengwasexpelledfromLuoyang,thecapital,andbecamethePrimeMinisterofHejian.ZhangHengcametoLuoyangforthesecondtimeandlivedfor26years.Inthese26years,althoughhisofficialpositionchangedseveraltimes,heservedasthesupremehistorianforthelongesttime.Hedidalotofscientificresearchwhenhewasappointedastheimperialhistorian.LingtaiisthelargestAstronomicalObservatoryinChinaduringtheEasternHanDynasty,whichwasusedfor250years.ZhangHengnotonlywrotesomeimportantscientificworkssuchasLingxian,earthquakecountermeasures,andnotesonthearmillarysphere,butalsodesignedandcreatedsomeingeniousinstrumentssuchasthearmillarysphereandtheHoufengseismograph,makingoutstandingcontributionstomankind.
InLingxian,ZhangHengexplainedindetailthenaturalphenomenaofthechangeoflunarphenomenaandtheoccurrenceoflunareclipse.Afterscientificanalysis,manyscientificopinionsareputforward.HerecordedthestarsintheskywhenhewasobservinginLingtai.Thereare2500brighterstars,124regularstarsand320namedstars.Thisisroughlythesameasthestatisticsofmodernastronomythat2500-3000starscanbeseenwiththenakedeyeatthesametimeandplace.ThenumberofstarsobservedinLuoyangatthattimeisbasicallythesameasthatobservedinmoderntimes.Therefore,healsodrewtheLingxianmap,whichistheearlieststarmapinChina.