The recipes of Ancient Rome were quite heavy on herbs and spices, so they were anything but bland. Instead of salt, they used liquamen/garum, which is a fermented fish sauce similar to colatura/nuoc mam/nam pla. I've cooked quite a few of them. My web page (from around 20 years ago, with lots of dead links) is at http://web.onetel.com/~hibou/Apicius.html

The complete text (in Latin) of Apicius's De Re Coquinaria is here: http://users.ipa.net/~tanker/apicius.htm

In addition to Apicius, there are recipes in De Agri Cultura by Cato.