Arches and peaks over Windows on older buildings-reason for this design?

[One Shot]

I think the White House has this feature where the window trim above alternates. What is the meaning of this?

[Gistok]

It's just a common feature of Palladian Architecture....
https://en.wikipedia.org/wiki/Palladian_architecture

One of the most famous examples [[besides the White House)... is the Banquetting House in London.... the only surviving part of the vast Palace of Whitehall that was ever built... [[much of what was built of the incomplete palace was destroyed in a great fire)...
https://commons.wikimedia.org/wiki/F...rt_Project.jpg

[beachboy]

It's just a common feature of Palladian Architecture.... One of the most famous examples [[besides the White House)... is the Banquetting House in London.... the only surviving part of the vast Palace of Whitehall that was ever built...

Yes and no ... alternating arched and pointed pediments can relieve boredom across an otherwise bland facade, as in the North Front of the White House. In concept [[but not in execution) similar to the mediaeval technique of varying a cathedral ceiling's ridgeline trajectory slightly [[by a few degrees) prior to or at the crossing, to relieve the boredom of a long vista. [[Religious explanation: to indicate the imperfection of man's works...) The US National Cathedral uses this technique where its eight-bay nave connects to the five-bay chancel and its three-bay transepts via the crossing - also, some of the massive piers that support the crossing [[bell) tower are said to be out-of-plumb by more than two inches:

https://www.washingtonpost.com/enter...5f1_story.html

Whitehall Palace actually was the largest palace in Europe during the latter years of its useful life [[1530-1698), more of a warren [[approx. 1,500 rooms) of heterodox styles than a grand structure like the US Capitol Building. As Gistok notes, after two disastrous fires it was not rebuilt [[altho' there were monumental plans, e.g., by Inigo Jones and Christopher Wren) due to financial constraints. [[Overview at: https://en.wikipedia.org/wiki/Palace_of_Whitehall)