Due to Attila bug which cannot be fixed you can see blank window for description of roman barracks lvl 1. Besides standard recruitment of low/mid units (there are too many of them, this causes blank desc.) and public order bonus they use food consumption = very low or none + maintenance cost = 100.
Tier 2 Palatium: 250/25;
Tier 2 Comitatenses: 200/25;

Tier 1 Garrison 100/10;