A cost-efficient way to enhance security in a building/factory/hospital/campus is to use the existing infrastructure:

During the day, security guards watch the monitor in the control room.

At night and weekends, surveillance can be performed remotely at a central monitoring station serving several companies.

Built-in motion-detection can trigger an alarm and start recording.

In case of an alarm, the security manager can view the images from the nearest PC in the building or remotely from any PC connected to the Internet.

The police can remotely follow what is going on in the building

The images can either be stored at a computer in the building and/or at a host computer at an ISP.

Storing images at remote locations eliminates the risk that the intruder will destroy the evidence.

The staff at the computer department can choose either to develop a program in-house or purchase specific surveillance software available from several vendors.