Few under the age of 40 can remember when the city centre was a place where vehicles and pedestrians could enter and leave without restriction.
Tight security has become the norm. Uniformed police officers always wear protective flak-jackets, move in pairs and carry handguns, rifles or machine-guns. Patrols of armed troops are common.
For much of the past year it has been impossible to travel into Belfast without passing through a police roadcheck with officers standing in the road to check drivers. Other officers stay on the pavements providing cover.
All major roads are covered. Some minor roads have been sealed off which means vehicles have no option but to take their place in the queues to be checked. Many vehicles are waved through while others are stopped and the driver asked for his destination.
Particular attention is paid to vans, since these have often been used by the IRA to transport large bombs. In most cases, however, car boots are not searched, since the primary purpose of the checks seems to be to deter the bombers rather than catch them. The theory, which generally holds good, is that bombing teams will not attempt to bluff their way through such checkpoints and so will regard the road as impassable.
Such measures are not popular with the public, since traffic is inevitably delayed, but the almost universal feeling is that they are a necessary inconvenience.
This general tightening of security was put into operation after the IRA reverted to the practice of placing large bombs close to the city centre. Some of these devices wrecked entire streets.
Some roadchecks are slightly different in that a police officer or soldier in a Land-Rover feeds vehicle registration numbers into a computer. This then responds with a code which indicates that the driver should be let through, stopped and questioned or subjected to a thorough search.
In the early 1970s there were so many bombs in Belfast that the authorities responded by erecting a 'ring of steel' around the city centre.
This entailed placing high railings around the central segment and limiting access to a number of permanently-manned entrances. The authorities created a new corps of uniformed 'civilian searchers'.
The searchers continue to function, and the ring of steel is still in place. Most private vehicles are excluded from the centre while buses are checked before being allowed in and pedestrians are liable to be checked.
Despite this, bombs and incendiaries still go off in and around the city centre in continual reminders that security can never be absolute. But few doubt that without the security the city centre would by now be a wasteland.
Taken together the measures may sound oppressive, and they certainly seem extraordinary to many tourists. For local people, however, familiarity has bred acceptance and the abnormal is now accepted as the norm.