Go Outside

Not to a city, but to a park or a hike in the woods (desert, mountains, beach, whatever you have). Numerous studies have shown that taking a walk in nature has increased memory retention, immune function and overall well-being. Cities require constant attention and strain your brain further rather than allowing anytime to rest. This is also true of constant stimulation, through electronics, technology, city noise, etc. The fact that your brain is always on at 100% limits the amount of time your brain can spend replenishing itself and your body and creating lasting memories. So take a break and go enjoy some of that God's green (brown, white, purple majesties) earth.

Here a list of other articles and studies citing this benefit:
Bergman, et al. in the Psychological Science Journal
Boosts to the Immune System from the NY Times
Psyblog
Even looking at nature pictures improves memory, Physorg.com

There's loads more if you care to look as well!