Since we're using Drush, the easiest way to get started with a new Drupal-installation was by downloading the core with the following Drush-command:
drush dl drupal
This installs the latest stable Drupal 7 release.
Since Drupal 8 is out as a beta-release we can download the latest Drupal 8 release with the following command:
drush dl drupal-8
If you would like to choose which version to download, you can get an overview of the releases by typing the following command:
drush dl drupal-8 --select --all
This will output an overview like this which allows you to choose which version to download: