What are these?

The spiky rings in these 2 pictures.
I can't remember seeing them anywhere else.
The island along the Watchtower Coast.

And Lion's Arch - right in front of the Keep gate.

Perhabs to build a fire in or something? Never really thought about it honestly, but its nice of you to bring it up, now I'm kinda wondering aswell. Looking at how its placed on the island, it seems its somewhat useful to be lit, but the position in LA doesnt make any sence then. As an audicy it makes no sense either. Perhabs some sort of acient way of transporting? Blink blink between shrines

i would guess a shrine or potal of some sort (HUMAN SACRIFICES ANYONE!?)

Krytan architectural designs?
Perhaps Krytans just like spires...

I always thought it to be some kind fo rez shrine. I was really hoping that the area would be used during Wik but it never turned out that way. That island and the floating castle are nice mysteries.

Outdoor BBQ pit.

They look like podia for announcements. Look at where they are placed, the one in LA is infront of the large square. The one by the castle is infront of it as well. Like scribes would announce important messages to the people

announcements? the one in watchtower coast is good to make announcements to the scales patrolling the coastline or shouting Monty Python quotes at the keep guards - there are no people there - ever and the terrain between the edge of the island where the thing is and the keep gates seems rugged and not suited for a place of gathering . They are both in front of a keep - and both of them keeps seem to have the same tilted forward model of a tower.
which is weird.

its some kind of ritual place...maybe a beam of light comes out of it...something of that sorts

my best guesses (prolly also correct ones D ):

1st pic: lighthouse (so boats don't crash around kryta although position is kinda fail )

2nd pic: a place for bonfire (to light the city during night and keep watchmen warm and stuff. you can see those in many medieval themed movies.)

Random 3d landscape flair.

Like a warning pyre type of thing? Watchtower cause well it's a watch tower and can be seen from a decent distance. LA to warn the townspeople.

just a thought?

Maybe the watchtower place was abandoned :S I can speculate a large number of things, like the water creeping up slowing through time creating that small river. If you think about it, if the water wasn't there before then there would be space for a large mass of people to gather.

But it's prolly 3d landscape flair like the dude said