The first program of urban renewal carried out by Caesar Divi Filius and his followers began in 33 BCE, when Caesar was consul for the second time and M. Agrippa was aedile. Agrippa eventually drained parts of the Campus Martius and dramatically expanded Rome's water supply, enabling him to build Rome's first imperial baths. One aspect of this earlier, programmatic transformation of the city that has up to now received little attention is the planting of a huge number of trees: in porticoes, in sanctuaries, beside temples, and laid out in large groves and wooded walks in the Campus Martius – especially around Augustus' gigantic Mausoleum. This 'greening' of Rome in the late 30s and 20s BCE was an important part of Augustus' revival of Archaic Roman religion, prompted by the writings of the antiquarians of the previous generation. Our best evidence for this comes from the poetry of Vergil, and from the genre of 'sacro-idyllic' painting – invented at Rome in these very years.