Drupal Dev Days has been a recurring event since 2010, when it got started in Munich. Since then it has changed location within Europe every year. This year it is being hosted in Seville, Spain from March 21-25. Dev Days is a special event, and I have my own very fond memories from previous years. Instead of being a general DrupalCamp, this is very focused on developers getting together and working on Drupal itself. There are definitely plenty of sessions to attend, where you can learn and grow. This year there is also a really great lineup of keynote speakers.
One thing that tends to set Dev Days apart is a heavy emphasis on sprinting, which makes for a great environment to dig into Drupal with a host of supportive mentors to help guide you, or bounce ideas off of. And you don't need to be a developer to take part in the sprints. There are a ton of fun tasks to help with. The sprints run every day, all the days of the event, so you can use it to fill some free time, or make a day of it. The camaraderie and learning keep hundreds of people coming back every year. If you've never attended a sprint, I highly recommend it as a way to not only learn Drupal, but to connect with people who can turn into lifelong friends.
We're excited to support Dev Days this year, and they will be handing out 5 free months of Drupalize.Me memberships. So go meet great people, enjoy the beautiful city of Seville, and get your Drupal on!