Gain impact in a pocket-size nook. This wedge of space behind a city townhouse looks like a sculptural installation, thanks to the perfect placement of furniture and plants. This room may not be officially sunken, but when it's viewed from above there's the pleasing illusion of a change in grade.Tile flooring creates a bold rhythm, while a trio of planters emphasizes each corner. Seating is aligned along the diagonal, creating a strong point of view. As pretty to look at as it is pleasant to sit and eat a meal on, the mint-green seating — a Lutyens bench and two midcentury wire armchairs — is lovely and lighthearted. The scalloped petal table looks like a flower from above.Can you say "sweet retreat"?