Cook shrimp in 1 quart boiling water 3 to 5 minutes or just until shrimp turn pink; drain. Rinse with cold water, and drain. Peel shrimp, leaving tails on; devein, if desired.
Line a large platter with romaine lettuce leaves. Mound Greek Potato Salad in center. Arrange shrimp, iceberg lettuce, beets, cucumber, and, if desired, tomato around potato salad. Sprinkle with olives and feta cheese. Top with bell pepper slices, and, if desired, anchovies; sprinkle with oregano. Drizzle with vinegar and oil just before serving.