Unless something breaks the glass or the electrical system, a neon sign can last 30 to 50 years.
In May of this year, a restaurant owner in Los Angeles tore down a wall and found a neon light still lighted, hidden behind the wall. It had been glowing steadily for about 77 years!

Las Vegas

The bright neon skyline is the symbol of Las Vegas. This is partly because it is a big tourist city. Neon shows off the attractions.
Las Vegas is so hot that tall buildings are hard to keep cool. Until the 1980s, most buildings were only one or two stories. The buildings didn't stand out. But the neon did.
The dry air in Las Vegas makes neon shine in crisp lines. Because the city is built on flat land, people can see all the lights shining together.
The neon lighting there is so bright that it can be seen from space.

Standing out

Neon signs are often bigger than the buildings they advertise. A sign might weigh several tons and be 200 feet high, as tall as a 20-story building.
Elevators or a system of ladders are often built inside the signs so workers can maintain them.
Neon sculptures may fill up huge spaces. For example, in Chicago's O'Hare Airport, a neon sculpture lights the ceiling of a walkway.