Image 1 (IMAGE) University College London Caption Photo of in situ water pipes leading to a drainage ditch near Pingliangtai's southern gate. Credit Yanpeng Cao Usage Restrictions For educational and editorial purposes only License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.