To recap: there is the terrace proper, and there is the roof...little, stolen bits of it.
The floor of the terrace is surrounded by walls, but is open to the sky, a beautiful thing. It faces east, so receives wonderful morning sunlight (making this a happy apartment), which persists until the sun is overhead and starts to slide west...anything from about 12pm to 3pm, depending on season. The roof-parts on the edges keep the most sun, right until 5 or later, and that's where the sun-loving herbs and perennials perch.
This side of the terrace is the coolest, with the sun at its back in the south, the wall making shade. Japanese ribbon grass, hosta, boxwood...begonia and impatiens as annual colour spots. The cliches are welcome here.
Hosta "Fragrant Bouquet" is just that. Have you ever sniffed a hosta flower? Well, do. Dee-licious.
This terrace seems to get smaller and smaller. So every plant counts. Flowers' opening become events. The most lowly annual is seen in a new light.