Under the Millennium BCP bank headquarters in Rua Augusta (enter round the back), the Archaeological Centre offers a glimpse of what's lurking below the Baixa. In Roman times, this was a river beach, where locals made sauces by mixing fish and shellfish bits with salt, spices and herbs. The ingredients were then put in tanks and left to rot over time into a suitably tasty decomposed mush. When the bank wanted to redo its head office in 1991, the construction teams unearthed the ancient complex. Experts were called in and the centre opened to the public in 1995. On display are artefacts found during the dig, as well as ancient walls, a holding tank and an intact section of mosaic floor.