1937年,日(ri)人鳥(niao)山(shan)喜一(yi)、藤(teng)田(tian)亮策等(deng)對八(ba)連城(cheng)進(jin)行了(le)調查,并對八(ba)連城(cheng)內(nei)城(cheng)宮殿(dian)址進(jin)行了(le)盜掘(jue)。
中華(hua)人民共和國成(cheng)立以后,吉林省(sheng)各級文物(wu)管(guan)理(li)部門對城(cheng)址開展了(le)多次調(diao)查和著錄工作。
2004至2008年,吉林省文物考古研究所、吉林大學、琿(hun)春市文物管(guan)理所等單位,對(dui)城址(zhi)進(jin)行了主動發掘。主要清理了一、二號宮殿基(ji)址(zhi)及其附屬建筑(zhu)(zhu)遺跡,城門址(zhi)等。出(chu)土大量磚、瓦類建筑(zhu)(zhu)構(gou)件。
經考古(gu)發(fa)掘確認(ren)的城門有兩(liang)處,分別為外城南(nan)(nan)門址(zhi)和內(nei)城南(nan)(nan)門址(zhi)。外城南(nan)(nan)門址(zhi)規(gui)模(mo)較小,單門道(dao),東(dong)西(xi)(xi)寬約(yue)3.2、南(nan)(nan)北(bei)(bei)(bei)長(chang)約(yue)5.2米(mi)(mi),直(zhi)接利(li)用城墻(qiang)墻(qiang)體作為城門兩(liang)側(ce)的墩臺。內(nei)城南(nan)(nan)門為建有夯土臺基(ji)(ji)(ji)的地面(mian)建筑(zhu)。臺基(ji)(ji)(ji)呈長(chang)方形,南(nan)(nan)北(bei)(bei)(bei)寬16.2米(mi)(mi),東(dong)西(xi)(xi)長(chang)27.4~28.6米(mi)(mi),東(dong)西(xi)(xi)兩(liang)端正中與城墻(qiang)相(xiang)接,現高0.6~0.8米(mi)(mi)。臺基(ji)(ji)(ji)上可見面(mian)闊五間(jian),進(jin)深二間(jian)的圓形柱礎基(ji)(ji)(ji)礎。臺基(ji)(ji)(ji)南(nan)(nan)、北(bei)(bei)(bei)兩(liang)側(ce)各(ge)有三條兩(liang)兩(liang)相(xiang)對,以(yi)黃色(se)夯土構筑(zhu)的踏道(dao)。
內(nei)城(cheng)的縱(zong)向中軸線上,有(you)2座(zuo)宮殿址(zhi),分別為一、二號宮殿址(zhi),兩座(zuo)宮殿址(zhi)兩側均(jun)有(you)附屬建(jian)筑(zhu),東西(xi)兩端各與(yu)一條(tiao)南(nan)北向長廊相(xiang)接,兩殿址(zhi)間有(you)一“十”字形建(jian)筑(zhu)臺基(ji)建(jian)筑(zhu)。
城內出(chu)土(tu)遺(yi)物以建(jian)筑構件(jian)為(wei)(wei)(wei)主,包括(kuo)板瓦(wa)(wa)、筒瓦(wa)(wa)、瓦(wa)(wa)當、獸頭、套獸、鴟尾(wei)、柱圍等。瓦(wa)(wa)件(jian)多(duo)為(wei)(wei)(wei)青灰色,但仍(reng)不乏為(wei)(wei)(wei)數(shu)(shu)不少(shao)的黃、綠(lv)釉琉璃瓦(wa)(wa)件(jian),瓦(wa)(wa)當當面紋(wen)飾以六(liu)瓣和(he)八瓣蓮花紋(wen)為(wei)(wei)(wei)主,另見有(you)花草(cao)文、乳丁紋(wen)等。出(chu)土(tu)的瓦(wa)(wa)件(jian)中有(you)相(xiang)當一部分瓦(wa)(wa)身凸面帶有(you)文字,或(huo)戳印(yin)、或(huo)刻畫,陰文、陽文均有(you),多(duo)數(shu)(shu)為(wei)(wei)(wei)漢字,少(shao)量為(wei)(wei)(wei)刻畫符(fu)號,累計出(chu)土(tu)九十余種。
該城(cheng)的布局(ju)與渤(bo)海(hai)上京、中(zhong)京相仿,均效仿于唐長安城(cheng),具有重要的歷史價值。
從(cong)城(cheng)(cheng)(cheng)址(zhi)(zhi)(zhi)規模、布(bu)局、主體(ti)建筑形式設計等方面比(bi)較,八連城(cheng)(cheng)(cheng)城(cheng)(cheng)(cheng)址(zhi)(zhi)(zhi)與渤(bo)海中京顯德府城(cheng)(cheng)(cheng)址(zhi)(zhi)(zhi)(和龍(long)西(xi)古城(cheng)(cheng)(cheng))極為相似。這兩座城(cheng)(cheng)(cheng)址(zhi)(zhi)(zhi)的發(fa)掘,為渤(bo)海及東(dong)北亞都(dou)城(cheng)(cheng)(cheng)研究提(ti)供了重要的考(kao)古學(xue)資料。
渤(bo)(bo)海(hai)國(guo)(guo)城(cheng)(cheng)(cheng)(cheng)址(zhi)。位于琿(hun)春(chun)市國(guo)(guo)營良種場內,東距琿(hun)春(chun)市6公(gong)里,北l公(gong)里是(shi)(shi)圖(們(men))琿(hun)(春(chun))公(gong)路。城(cheng)(cheng)(cheng)(cheng)址(zhi)由內外兩城(cheng)(cheng)(cheng)(cheng)組成(cheng)。外城(cheng)(cheng)(cheng)(cheng)平(ping)面(mian)略(lve)呈(cheng)方(fang)形,城(cheng)(cheng)(cheng)(cheng)墻(qiang)(qiang)(qiang)土筑(zhu)。周長(chang)2894米(mi)(mi)(mi)(mi),北墻(qiang)(qiang)(qiang)712米(mi)(mi)(mi)(mi),南墻(qiang)(qiang)(qiang)701米(mi)(mi)(mi)(mi),東墻(qiang)(qiang)(qiang)746米(mi)(mi)(mi)(mi),西墻(qiang)(qiang)(qiang)735米(mi)(mi)(mi)(mi)。城(cheng)(cheng)(cheng)(cheng)有4門,分別(bie)設置于各(ge)墻(qiang)(qiang)(qiang)的(de)中部,城(cheng)(cheng)(cheng)(cheng)墻(qiang)(qiang)(qiang)外6米(mi)(mi)(mi)(mi)處有護城(cheng)(cheng)(cheng)(cheng)河遺(yi)跡。內城(cheng)(cheng)(cheng)(cheng)平(ping)面(mian)呈(cheng)長(chang)方(fang)形,周長(chang)l072米(mi)(mi)(mi)(mi),南、北墻(qiang)(qiang)(qiang)各(ge)長(chang)218米(mi)(mi)(mi)(mi),東、西墻(qiang)(qiang)(qiang)各(ge)長(chang)3l8米(mi)(mi)(mi)(mi),有城(cheng)(cheng)(cheng)(cheng)門3處,分別(bie)修建于南、東、西墻(qiang)(qiang)(qiang)的(de)中部。內城(cheng)(cheng)(cheng)(cheng)中央有一(yi)宮殿址(zhi)臺(tai)基(ji),臺(tai)基(ji)北另有殿址(zhi)3處。出土文物有蓮花紋(wen)瓦(wa)當、“文字”瓦(wa)、浮雕式牡丹紋(wen)和忍冬(dong)紋(wen)磚、綠釉琉璃瓦(wa)等(deng)。八(ba)連(lian)城(cheng)(cheng)(cheng)(cheng)是(shi)(shi)唐(tang)代渤(bo)(bo)海(hai)國(guo)(guo)東京(jing)龍(long)原府遺(yi)址(zhi),始建于唐(tang)德宗貞元元年(nian)(nian)(nian)(nian)(785)左右。唐(tang)貞元時,渤(bo)(bo)海(hai)第三代王大欽(qin)茂將其國(guo)(guo)都從上京(jing)龍(long)泉府遷至八(ba)連(lian)城(cheng)(cheng)(cheng)(cheng),唐(tang)貞元10年(nian)(nian)(nian)(nian)(794年(nian)(nian)(nian)(nian)),渤(bo)(bo)海(hai)成(cheng)王復遷上京(jing)后,八(ba)連(lian)城(cheng)(cheng)(cheng)(cheng),仍為(wei)渤(bo)(bo)海(hai)之(zhi)東京(jing)。公(gong)元926年(nian)(nian)(nian)(nian),遼(liao)滅渤(bo)(bo)海(hai),八(ba)連(lian)城(cheng)(cheng)(cheng)(cheng)遂廢。古(gu)城(cheng)(cheng)(cheng)(cheng)內現已辟為(wei)農田。
1961年吉林省(sheng)人民委員會公布(bu)為(wei)吉林省(sheng)重點文物保護單位。
2001年6月25日國務院公布(bu)為全國重點文物(wu)保(bao)護單位(wei)。