Shapes

Every building is made up out of shapes, examples would be squares, rectangles, triangles, sphere, circles, arches, domes, etc. Some shapes have unique properties.

Shapes featuring straight lines are very controlled and human as there are no straight lines in nature. This makes rectangles, squares, triangles, octagons, pentagons, etc. all very human shapes which work particularly well in industrial or modern style or in general in urban settings.

Circles have an other interesting property, they have no visual focus point. One can follow the outline of a circle and won't find a place to focus their attention on, as it's everywhere the same. Architects exploit this to draw attention to parts they want to feature. If we take a half sphere, a dome, and stick something we want to feature on top of it in the center, all the focus will be drawn to this thing, as there are no other visual focus point on a perfect dome. Examples, a church with a dome roof featuring an cross in the center, a mosque with a cressent moon on top or a theater with a pagado/pinacle on top.

Domes, arches and triangles have another interesting property with regards to structural integrity. They distribute energy/weight very effectivelly to the legs of the shape which then can be transfered to the ground. This is why you will see a lot of arches and traingular shapes in historical styles, as they used this property to support their structures. Domes feature the same property, and perfectly distribute the weight to the edges, this means you can have a large open space under a dome. An example would be the inside of a theater, where there are no pillars among the seets to support the roof, as it's self supporting, making it so that everyone has a clear view at the stage.

To illustrate how shapes affect the feel of architecture i'll use Lord of the Rings:
Circles - The shire features virtually no straight lines, making hobbits feel very natural and gentle
Angular - The human parts of LOTR feature a lot of angular elements, angles being very human this makes it fitting
Transitional - Ofcourse there are also transitional styles, Elven for example uses as well angular as circular/flowing designs making this a more challenging buildstyle. It also suggestive about the nature of the elven race.

Lines

Lines work the same as they do in fashion, vertical lines make things look thinner and taller, horizontal lines make stuff look fatter and wider. Vertical lines come in handy on parts of builds where you want to exagurate the height, an example would be a tower. Horizontal lines are typically used to show various floors on the exterior, these also act as supporting lines to easely divide the building in parts, which makes it more easely comprehensible.