Abstract: Barrier units for use in constructing barriers and a method for constructing the barrier units are disclosed. The barrier units are suitable for a variety of purposes including the construction of security barriers for sensitive facilities or temporarily halted ships. The barrier units of this invention can also be used as buffers between marine vessels or between marine vessels and harbor facilities to prevent damage to vessels. The barrier units of this invention can include vertical uprights, vertical protective mesh, submarine protective mesh, impalement spikes, walkways, and internal compartments for storage or occupation by security personnel. The security barrier can include lights or other electronic devices for providing security. The barrier units can be used to provide security for land-based facilities and for barriers between lanes of traffic.