District of Columbia is about 746 times smaller than Greece.

Greece is approximately 131,957 sq km, while District of Columbia is approximately 177 sq km, making District of Columbia 0.13% the size of Greece. Meanwhile, the population of Greece is ~10.5 million people (9.9 million fewer people live in District of Columbia).
Tip: This to-scale comparison of Greece vs. District of Columbia uses the Mercator projection, which distorts the size of regions near the poles.