Limestone was most popular in the late 19th and early 20th centuries. Train stations, banks and other structures from that era are normally made of limestone. Limestone is used as a facade on some skyscrapers, but only in thin plates for covering rather than solid blocks. In the United States, Indiana, most notably the Bloomington area, has long been a source of high quality quarried limestone, called Indiana limestone. Many famous buildings in London are built from Portland limestone.

Limestone was also a very popular building block in the Middle Ages in the areas where it occurred since it is hard, is durable, and commonly occurs in easily accessible surface exposures. Many medieval churches and castles in Europe are made of limestone. Beer stone was a popular kind of limestone for medieval buildings in southern England.

Limestone and marble are very reactive to acid solutions, making acid rain a significant problem. Many limestone statues and building surfaces have suffered severe damage due to acid rain. Acid-based cleaning chemicals can also etch limestone, which should only be cleaned with a neutral or mild alkaline-based cleaner.

Other uses include:

• The manufacture of quicklime (calcium oxide) and slaked lime (calcium hydroxide);
• Cement and mortar;
• Pulverized limestone is used as a soil conditioner to neutralize acidic soil conditions;
• Crushed for use as aggregate—the solid base for many roads;
• Geological formations of limestone are among the best petroleum reservoirs;
• As a reagent in desulfurizations;
• Glass making, in some circumstances;
• Added to paper, plastics, paint, tiles, and other materials as both white pigment and a cheap filler.
• Toothpaste
• Suppression of methane explosions in underground coal mines
• Added to bread and cereals as a source of calcium

from wikipedia.org