Three riddles in the form of Shakespearean sonnets

Here are three riddles for the history buffs out there. Which places are referred to in each of these below?

Her youth now having seeped through dingy cracks
That centuries have opened in her walls,
The metropole her vanished empire lacks,
As other tongues converse within her halls.
Across the strait an oriental shore
Observes the hazy vista towards the eve,
Of ancient domes that hug the city floor:
A tapestry that many cultures weave.
The envy of the Tatar and the Frank
Who would with purple robe themselves adorn,
The city that bestrode old Europe's flank
Would reign a thousand years upon the Horn.
   And through her streets yet wander silently
   Forgotten memories of majesty.

A wintry snap in autumn comes to call:
The scent of coal is frozen in mid-air
And wraps the city in a murky pall
That hangs above the buildings on the square.
A lofty castle stands above the town
Where silhouetted spires appear to grow;
Within her gates once lay the Empire's crown
Upon a Luxemburger's kingly brow.
(A fabled bridge now bears his royal name,
As does a school of great antiquity.)
But soon his town would pale before the fame
Of regal Habsburgs' grander dignity.
   Though tyranny for forty years held sway,
   A fortnight saw it quickly swept away.

Along the river's mouth where swampy land
Was captured from a fading Baltic realm,
A capital arose to take command
Of empire from an older eastern helm.
A beardless monarch bent upon reform,
Who sought to emulate the occident,
Created her according to the norm
Of finer cities where his youth was spent.
Compared with these her life has yet been brief,
Though long enough more than one name to bear.
In time of war her people, brought to grief,
Endured privation's curse and deep despair.
   And when the monarch's dynasty had ceased,
   The seat of empire moved again back east.

© David T. Koyzis, 1989