AbstractIn this paper we introduce a public resource named BACO (Base de Co-Ocorrências), a very large textual database built from the WPT03 collection, a publicly available crawl of the whole Portuguese web in 2003. BACO uses a generic relational database engine to store 1.5 million web documents in raw text (more than 6GB of plain text), corresponding to 35 million sentences, consisting of more than 1000 million words. BACO comprises four lexicon tables, including a standard single token lexicon, and three n-gram tables (2-grams, 3-grams and 4-grams) with several hundred million entries, and a table containing 780 million co-occurrence pairs. We describe the design choices and explain the preparation tasks involved in loading the data in the relational database. We present several statistics regarding storage requirements and we demonstrate how this resource is currently used.