1The Millennium Tower (USA)
Just recently, the European Space Agency has released detailed data from satellite imagery that shows the skyscraper in San Francisco's financial district is continuing to sink at a steady rate — and perhaps faster than previously known. (Source | Photo)
Several measures have been taken to stop Venice from sinking, including the Venice Tide Barrier, and it was believed that the water levels had stabilized. But Scripps Institution of Oceanography at UC San Diego has revealed that the city is still sinking and leaning by an unprecedented 2mm per year over the last decade, with certain northern sections are dropping between 2 to 3mm per year, while the southern lagoon is falling away by 3 to 4mm over the same period.
National Research Council spokesman Luigi Tosi said that Venice's sinking was a combination of land subsidence and sea level rise. (Source | Photo)
3 Sinking Bell Tower (Philippines)
4Palacio de Bellas Artes (Mexico)
The city, built on an island in the middle of a lake around 1325 AD, was plagued by the provision of potable water for centuries. Deforestation depleted springs that had supplied the city with fresh water via aqueducts in the 19th century. The first fresh water well was built in the city center in 1857, and by 1900 there were hundreds of wells sucking water from the underground aquifer.
You can see where this is going.
Some parts of Mexico City have dropped more than seven meters (23 ft) since 1891. Parts of the city center sank more than a meter between 1948 and 1951, and another meter by 1960. The city fell two meters below what remained of Lake Texcoco, posing a serious risk of flooding during the rainy season. In 1950, new wells were drilled south of the city reducing central city sinking to its current rate of about 10 cm (4 in) a year. It helped, but buildings in the southern part of the city began to sink more rapidly. (Source | Photo)
5Taj Mahal (India)
The ebony foundation of the palace, built on the Yamuna River, requires a steady stream of moisture to maintain stability. Due to climate change, the river now dries up completely during the summer months, causing the breakdown of the foundation and resulting tilt. (Source | Photo)
6Milwaukee, Wisconsin (USA)
In the city's Third Ward, the bricks are starting to crumble and crack, and the buildings are beginning to lean. But why?
Much of Milwaukee was built on a marsh. Around the turn of the century, contractors used steam-powered pile drivers to sink into the soggy land below thousands of wood pilings. Concrete was then placed on top of those pilings as a foundation for the buildings to come.
The technique of setting foundations on wood pilings is nothing new and had been used in Europe for centuries, but, "The pilings need to be kept wet. This sounds counter-intuitive, but things that are wet permanently rot slower," UW-Milwaukee Professor of Geosciences Doug Cherkauer said. When the city's water table receded (for reasons that are still unknown), the pilings were exposed to air and — well, you can guess the rest. (Source)
7Leaning Tower of Pisa (Italy)
The tower is slightly curved from attempts by various architects over the centuries to keep it from leaning more or falling over. In 2008, engineers stated that Pisa had stopped moving, marking the first time in its history that it has not been slowly leaning further to one side. They expect it will remain stable for at least another 200 years. If another intervention is then required, the technology available to make improvements could be far more advanced and preserve the tower for 800 more years. (Tourists, you have plenty of time to post photos of yourself "holding the Tower up " to Instagram. How awesome is that?)
Below a seven-meter layer of sand is a 30-40 meter thick bed of slippery clay that doesn't cope well with the weight of the structures. Until 1968, local building codes had no restrictions on the type of foundation that could be used for multistory buildings. Ideally, they should reach bedrock, which here is about 50 meters deep, but the buildings on Santos' waterfront have foundations that are only 4 or 5 meters (13 to 16 feet) deep. After the lean in the first building was visible, a requirement was added to the city's building code to deepen the foundation for tall buildings.
Surprisingly, people continue to live in these apartments, and the main problem they face right now is a devaluation of their property — prices of the condos plummeted after the lean became visible to the naked eye many years ago. (Source)