Luy Lâu (Vietnamese) or Leilou (Chinese: Traditional 羸婁, Simplified 羸娄, Pinyin Léilóu) (< Middle Chinese ZS *liuᴇ-ləu < Eastern Han Chinese *lyai-lo^[1]) was the first capital of the Han commandery of Jiaozhi (Giao Chỉ) from 111 BC following China's conquest of Nanyue/Nam Viet till 106 BC. It was also the headquarters of the larger province of Jiaozhou (Giao Châu) and the center of China's maritime trade on the Gulf of Tonkin and South China Sea. The old citadel is at Xã Thanh Khương in Thuận Thành in the province of Bắc Ninh.^[2][3]

Luy Lâu became a major center for Buddhism in Vietnam.^[4] Although the Roman embassies probably arrived at the later capital Long Biên, it may have been the earlier Luy Lâu that was the origin of Ptolemy's Cattigara.

• List of capitals of Vietnam
• Long Biên