To cook the pasta, bring 4 quarts water and 1 tablespoon salt to a boil.
Add pasta and cook according to package instructions, about 7 to 10 minutes.
Drain well and rinse with cold water.
Meanwhile, to make the dressing, in a small bowl whisk oil, vinegar, garlic, oregano, 1/4 teaspoon salt, and 1/8 teaspoon pepper.
In a large bowl, combine cooked pasta, cucumbers, onion, tomatoes, feta, and olives.
Drizzle with dressing.
Toss gently until uniformly combined and serve.