Are you on this site because you are considering using time clocks for your employees? These clocks help them to log accurate hours and they keep people from abusing the system. Without them, some people might claim that they were at work when they were not, either because they had not arrived on time or because they had gone home early, making you pay them for time that they were not doing anything of value. There are a few different clocks designs out there, including some that work on computers, but the most traditional option is a mechanical clock that mounts on the wall.
In order to get people to use these clocks, one thing that you have to consider is where you are going to position them. Conventional wisdom says that you should put them on the wall near the main entrance. Workers can then punch in when they get to work and punch out when they leave. The issue with this is that, unless your building is very small, workers are probably not all going to come to the same door. Some are going to come through the front and head for their offices, some are going to come to the side door because they need to drop off deliveries or work with other ones that are being delivered, and some employees may use a different door just because they work the second shift and they do not want to fight through all of the people who are leaving after the first shift.
As you can see, it is sometimes better to put the clock inside of the building, at a central location. That way, everyone can get to it with ease, no matter where they arrived or where they work in the building. This also means that there will never be a logjam at the front door when the shifts change, with people trying to clock in and out at the same time.
Remember, for your employees, clocking in on time is very important because it dictates how much they get paid for the day. It could also make them eligible for bonuses if they are never late. You want to set the clock up in a place that will make it easy for them to get to it and use it correctly, or you are constantly going to get complaints about how their recorded times are not accurate.