[Solumina]

Um...that isn't how the hight restrictions work, actually things are a good bit more limited than that. Buildings get a high restriction based on the size of the building front. So essentially you can have tall(ish) buildings but they have to be really wide and it has nothing to do with the monument, although that is the tallest building in DC by a long shot that is mainly because it was built before there were any height restrictions.

That being said there are plenty of buildings tall enough for Spider Man to swing from plus he could always just get out of DC and go to Vienna or something where there aren't such strict limitations.