When the International Rose Test Garden was founded in 1918, Portland was already the City of Roses, but the free garden set the status in stone. Originally created to preserve English roses at risk during WWI, it's now a gallery of sorts, displaying a variety of cultivars of varying size, color, and scent. If you're here in peak season, leave lots of time to admire the insane variety and unique individuality of each flower. If you're visiting at a less-than-optimal time for blooms, there's still bound to be stuff to see. Worst comes to worst and you're here in the dead of winter, the view from the top of the hill is pretty incredible.