As a city grows, so does the value of its land. The best way to capitalize on a commercial real estate investment is to build up - to offer more rentable space without having to buy more expensive (and heavily taxed) land to do it. In the 1850s, however, this posed some real problems. For one thing, building technology had not progressed very far. At that time the main technique used to construct walls was masonry - stone and cement. These [G 09 / load-bearing walls] could support structures only of a certain height. The higher the building, the thicker the walls had to be. And the thicker they were, the heavier, and thus the greater the chance that the entire building would sink. The record height for a load-bearing structure was the Monadock Building in Chicago, completed in 1891. It was 16 stories tall, and the walls on the first floor were 15 feet thick.
Another problem was human resistance: in the 1800s, as today, people balked at having to climb more than five flights of stairs. Thus, five stories was the practical limit for buildings at the time, if they were to be considered fit for human use.
The outlook changed in 1853, when [L3 201 / Elisha Graves Otis demonstrated his new invention, the safe elevator], at the Crystal Palace Exhibition. His was the first elevator with [I 011 / automatic safety brakes]. With such a device installed in a building, the height could now rise above the previous limit of five stories.
