Vienna was the putative capital of the Holy Roman Empire, and was starfortified following the Ottomans' unsuc-cessful siege in 1529.
The Linienwall, Emperor Leopold I's 1704 fortificational improvement, required all of the city's residents aged 18-60 to participate in its construction.

This earthen rampart, which was completed in only four months, was reinforced in 1738 with masonry.
The growing city's transportational needs did away with Vienna's heroic fortifications in 1896.

Luxembourg was quite possibly the most heavily-starfortified city in the history of starforts. What is today the nation of Luxembourg was a region possessed and/or administered by Spain, France, the Netherlands, Austria and Prussia, all of whom had an interest in fortifying the living snot out of its strategically-placed capital city.
Fortification began shortly after the city's founding in the 10th century.

Fort Thüngen, one of Fortress Luxembourg's Austrian-era eastern outerworks, is the only fully-restored fortification still standing, and you can read all about the late, great Fortress Luxembourg at its dedicated page.

The Habsburg mon-archy built a starfort on the island of Ada Kaleh, in the Danube River at what is now the border betwixt Romania and Serbia, in 1689. Fort and island spent the next two centuries being traded back & forth between the Austrians and Ottomans, though it doesn't appear that the fort was fought over...just lots of peaceful, if sullen, trading.

In 1972 the Iron Gate Hydroelectric Dam was unleashed on the Danube, completely submerging the island of Ada Kaleh. The island had been supporting a population of a few hundred folks mostly of Turkish descent, and their landmarks were planned to be re-erected on Şimian Island, about a dozen miles down the Danube. Apparently that process is still being discussed, but there's clear evidence that there already was a starfort on Şimian Island (see below).

Like any German city worth its salt, Moers (or Mörs, which is way cooler) had a schloss (castle). This castle was lovingy placed on an island in the mighty Rhine River, in the 12th century.

The river worked its Rhinian magic in the late 13th century, however, and readjusted itself to flow about five miles to the east of Moers. This unexpectedly left the schloss in a low, marshy area, which turned out to be a great place to build a starfort!

The Eighty Years' War (1568-1648) brought the Spanish, English and the "Oranges" (Dutch) To Moers: Spain held the town and built a lovely four-pointed starfort and outerworks, but the Siege of Moers (1597) won town and fort for Maurice of Orange (1564-1625).

Maurice was known as a military innovator, and a firm believer in the utility of the modern starfort. His breathtaking example of the Dutch style of starfortification was built at Moers at the very start of the 17th century.
Moers became Prussian at the beginning of the 18th century, and was briefly occupied by the French during the Seven Years' War (1756-1763)...after which Prussia's Emperor, Frederick the Great (1712-1786) ordered that Moers' lovely Dutch starfort be destroyed, perhaps due to its proximity to France. The city's pretty starry walls survived this strategic slight because they were needed as a dike to keep the city above water.

Dresden's first fortified walls were built in 1427. The right bank of the River Elbe was starfortified beginning in 1545, and the whole city was surrounded by starfortificational goodness by 1555.

The Napoleonic Wars began the process of Fortress Dresden's destruction, and by 1830 almost all of the city's walls were gone...leaving enough underground works to serve as air raid shelters during the Second World War, during which the RAF and USAAF did away with much of what remained of altendresden.

A major program to add extensive starfortish elements to Geneva's city walls got underway in 1547, which effort bore the fruit of the extended bastions we see in the top image, an illustration of the 1602 Escalade, an unsuccessful sneak attack on the city by the Savoyards.
The center image depicts Geneva in 1841, having massively starfortified itself after lessons learned during the Napoleonic Wars. Virtually all of these stellar fortifications were dismantled in the 1850's in the name of urban development.

Wee bits of Geneva's extensive fortifications linger today, perhaps most notably the Île Rousseau (lower image), previously known as the Isle des Barques (Island of Boats), which served as an island redoubt in 1841. Today a statue of 18th-century Genevan philosopher Jean-Jacques Rousseau stands sentinel thereupon.

The British under General James Oglethorpe built Fort Frederica on St. Simon's Island, Georgia, in 1736. This was the largest British fortification in the Americas at the time, which it needed to be, because the Spanish were already heavily invested in Florida, the border with which was just 30 miles to the south. It wasn't a matter of if, but when the Spanish would attack.

Around 630 British troops were stationed at Fort Frederica, and 500 colonists populated the fortified area directly to the fort's east.

The expected attack came in 1742, when 2000 angry Spaniards landed on St. Simon's Island and headed for Fort Frederica.

Oglethorpe's troops, including a number of Indians, met the attack with around 1000 men...and vanquished the wicked Spanish at the Battle of Bloody Marsh (July 7, 1742). Fort Frederica, and the British colony of Georgia, were saved.

Today Fort Frederica National Monument does an excellent job of pointing out where important parts of the fort were, but relatively little of it remains. This did not prevent me from visiting and enpicting what I could in 2017, the results of which one can see at the Fort Frederica page in this site's Starforts I've Visited section.