Here is a picture of a small part of a building.  The building is large, with a courtyard which can be glimpsed in a picture.  It would once have been owned by a very rich person, in an age when such people were a small minority, surrounded by very poor people.  Most of those would never have entered the building, or even the courtyard.  Even traders with business to do would have used a tradesmen’s entrance at the side or the back.  As late as the third quarter of the 20th century, some fairly ordinary houses sported the legend "Tradesmen’s Entrance".

The people who did use that main entrance would have been the friends and acquaintances of the owner – people whose social standing was not too far removed from that of the occupants.

Entrances, like the buildings they serve, have a significance far beyond the structural.  In this they resemble windows, porches and balconies.  The message implied by an entrance may be inviting, welcoming, friendly, impressive, aggressive, threatening, overpowering – you can probably add others.  They may serve to unite or divide, inclusive or exclusive.  Some entrances may give rise to positive feelings – those of theatres, cinemas, stadiums and sports fields: others may induce trepidation, as when we enter a hospital, or worse, a court or a prison.  And a few, a very few, entrances are really exits – the door to a death chamber, where a rope, an electric chair or a needle is ready for use.  Such are passed by a very few people, but there have been one-way entrances that many, even millions have entered, never to return.

Whether they led to concentration camps, gulags, or what you will, they were all based on an extreme version of the idea suggested at the top of the page – them and us.  It is not uncommon for entrances to bear a legend, and even the portals of bridges may be so adorned.  The Royal Albert bridge carries, in large sans-serif characters, this simple label –

I K BRUNEL

ENGINEER

Inscriptions like these "ARBEIT MACHT FREI" and "Work in the USSR is a matter of Honour and Glory" were placed over the entrances to camps.