1970年(nian)(nian),懷德縣(xian)文化部門對境(jing)內的(de)遺址(zhi)進行了全面的(de)普(pu)查(cha),在城址(zhi)內采集、征集各類文物數十件。1983、2009年(nian)(nian),通過第(di)二次、第(di)三次全國(guo)文物普(pu)查(cha),對城址(zhi)進行了系統的(de)調查(cha)和(he)著錄。
五家(jia)子城址周(zhou)長近3000米,具有州治(zhi)規(gui)模,可(ke)能(neng)為遼信州下轄之(zhi)州、縣城。
城(cheng)(cheng)(cheng)址分為(wei)(wei)內(nei)(nei)、外二城(cheng)(cheng)(cheng),城(cheng)(cheng)(cheng)垣均夯土構筑(zhu)。外城(cheng)(cheng)(cheng)大致呈南(nan)(nan)(nan)北(bei)(bei)向(xiang)的(de)(de)長方(fang)形(xing),東(dong)、西(xi)兩墻(qiang)(qiang)(qiang)長約(yue)823米(mi)(mi)(mi),南(nan)(nan)(nan)、北(bei)(bei)兩墻(qiang)(qiang)(qiang)長約(yue)609.5米(mi)(mi)(mi),周長約(yue)2865米(mi)(mi)(mi)。外城(cheng)(cheng)(cheng)殘(can)損嚴重,城(cheng)(cheng)(cheng)垣基(ji)(ji)本(ben)無存(cun),是否存(cun)有(you)馬面(mian)、甕(weng)門(men)等遺跡(ji)(ji)(ji)已(yi)不(bu)得而知。外城(cheng)(cheng)(cheng)四(si)(si)角(jiao)(jiao)建有(you)角(jiao)(jiao)樓(lou),東(dong)北(bei)(bei)角(jiao)(jiao)樓(lou)現存(cun)好,平面(mian)近(jin)圓(yuan)形(xing),直徑約(yue)12米(mi)(mi)(mi),殘(can)高(gao)(gao)約(yue)2米(mi)(mi)(mi),其(qi)余(yu)3處角(jiao)(jiao)樓(lou)地表僅見(jian)稍高(gao)(gao)于地表的(de)(de)殘(can)跡(ji)(ji)(ji)。外城(cheng)(cheng)(cheng)東(dong)墻(qiang)(qiang)(qiang)位置(zhi),距內(nei)(nei)城(cheng)(cheng)(cheng)南(nan)(nan)(nan)墻(qiang)(qiang)(qiang)約(yue)30米(mi)(mi)(mi)處,現存(cun)一高(gao)(gao)約(yue)6米(mi)(mi)(mi)的(de)(de)圓(yuan)形(xing)臺基(ji)(ji),疑為(wei)(wei)外城(cheng)(cheng)(cheng)東(dong)墻(qiang)(qiang)(qiang)甕(weng)門(men)的(de)(de)殘(can)跡(ji)(ji)(ji)。城(cheng)(cheng)(cheng)外10米(mi)(mi)(mi)處,東(dong)、西(xi)、北(bei)(bei)三面(mian)可(ke)見(jian)護城(cheng)(cheng)(cheng)壕遺跡(ji)(ji)(ji),唯東(dong)城(cheng)(cheng)(cheng)不(bu)見(jian)城(cheng)(cheng)(cheng)壕跡(ji)(ji)(ji)象(xiang),內(nei)(nei)城(cheng)(cheng)(cheng)位于外城(cheng)(cheng)(cheng)的(de)(de)東(dong)北(bei)(bei)角(jiao)(jiao),東(dong)、北(bei)(bei)兩墻(qiang)(qiang)(qiang)借(jie)用外城(cheng)(cheng)(cheng)的(de)(de)東(dong)、北(bei)(bei)二墻(qiang)(qiang)(qiang),另筑(zhu)西(xi)墻(qiang)(qiang)(qiang)和南(nan)(nan)(nan)墻(qiang)(qiang)(qiang)而成。內(nei)(nei)城(cheng)(cheng)(cheng)平面(mian)近(jin)正方(fang)形(xing),東(dong)、西(xi)兩墻(qiang)(qiang)(qiang)長約(yue)341米(mi)(mi)(mi),南(nan)(nan)(nan)、北(bei)(bei)兩墻(qiang)(qiang)(qiang)長約(yue)320.5米(mi)(mi)(mi),周長約(yue)1323米(mi)(mi)(mi)。其(qi)中(zhong)南(nan)(nan)(nan)墻(qiang)(qiang)(qiang)保存(cun)好,基(ji)(ji)寬約(yue)8米(mi)(mi)(mi),現高(gao)(gao)5~6米(mi)(mi)(mi),其(qi)余(yu)3面(mian)墻(qiang)(qiang)(qiang)體地表多(duo)僅存(cun)殘(can)跡(ji)(ji)(ji)。內(nei)(nei)城(cheng)(cheng)(cheng)四(si)(si)角(jiao)(jiao)構筑(zhu)有(you)角(jiao)(jiao)樓(lou),東(dong)北(bei)(bei)角(jiao)(jiao)樓(lou)即為(wei)(wei)外城(cheng)(cheng)(cheng)東(dong)北(bei)(bei)角(jiao)(jiao)樓(lou)。現存(cun)東(dong)南(nan)(nan)(nan)、西(xi)南(nan)(nan)(nan)角(jiao)(jiao)樓(lou),尤以東(dong)南(nan)(nan)(nan)角(jiao)(jiao)樓(lou)較為(wei)(wei)完(wan)整,平面(mian)近(jin)圓(yuan)形(xing),基(ji)(ji)寬約(yue)16米(mi)(mi)(mi),高(gao)(gao)約(yue)8米(mi)(mi)(mi)。內(nei)(nei)城(cheng)(cheng)(cheng)未見(jian)門(men)址與甕(weng)城(cheng)(cheng)(cheng)遺跡(ji)(ji)(ji)。
外(wai)城(cheng)(cheng)(cheng)地表遺物(wu)(wu)(wu)豐富(fu),尤以(yi)(yi)外(wai)城(cheng)(cheng)(cheng)南(nan)側(ce)近(jin)河(he)一帶(dai)遺物(wu)(wu)(wu)更為(wei)豐富(fu)。內(nei)城(cheng)(cheng)(cheng)遺物(wu)(wu)(wu)則非(fei)常零星,僅見少量(liang)(liang)細泥(ni)質(zhi)(zhi)灰(hui)陶(tao)(tao)片(pian)和白(bai)瓷片(pian),以(yi)(yi)及青磚(zhuan)和布紋(wen)瓦殘片(pian)。外(wai)城(cheng)(cheng)(cheng)遺物(wu)(wu)(wu)以(yi)(yi)陶(tao)(tao)、瓷器(qi)為(wei)主(zhu)。陶(tao)(tao)器(qi)以(yi)(yi)泥(ni)質(zhi)(zhi)灰(hui)陶(tao)(tao)為(wei)主(zhu),均(jun)輪制,火候較高、陶(tao)(tao)質(zhi)(zhi)堅硬(ying)。器(qi)形包括罐、甕(weng)、盆(pen)、壺等。陶(tao)(tao)器(qi)紋(wen)飾多樣,以(yi)(yi)多種(zhong)形式(shi)的附(fu)加堆紋(wen)為(wei)主(zhu),還(huan)可(ke)見篦齒紋(wen)、卷云紋(wen)等。另有少量(liang)(liang)的夾砂陶(tao)(tao),主(zhu)要出于城(cheng)(cheng)(cheng)外(wai)南(nan)側(ce),器(qi)形多較小,可(ke)能為(wei)青銅時代遺物(wu)(wu)(wu)。城(cheng)(cheng)(cheng)內(nei)出土瓷器(qi)均(jun)為(wei)白(bai)瓷,胎質(zhi)(zhi)粗糙,釉色泛(fan)黃,器(qi)形有碗、盤、碟等。
城址(zhi)雖未(wei)發掘(jue),城址(zhi)的(de)(de)年代、性質認定尚(shang)無(wu)充分(fen)證據,但城內(nei)出土遺物的(de)(de)特點表(biao)面,遺物多為遼金時期。《遼史》信(xin)州(zhou)條下(xia)記錄信(xin)州(zhou)轄(xia)三州(zhou)、二縣(xian)。五家(jia)子城址(zhi)周長(chang)近3000米,具有(you)州(zhou)治規模,可(ke)能(neng)為遼信(xin)州(zhou)下(xia)轄(xia)之州(zhou)、縣(xian)城。對研究當(dang)時的(de)(de)政治、經濟、軍事、文化、交(jiao)通(tong)等各方面都具有(you)較高的(de)(de)歷(li)史價值。