Ancient Romans most probably inherited their knowledge of barrel vaulting from Etruscans and the Near East. Persians and Romans were the first to use this building method extensively on large-scale projects and were probably the first to use scaffolding to aid them in construction of vaults spanning over widths greater than anything seen before. However, Roman builders gradually began to prefer the use of groin vault; though more complex to erect, this type of vault did not require heavy, thick walls for support (see below), and thus allowed for more spacious buildings with greater openings and much more light inside, such as "thermae".