A university town has two populations and only one of them is there in July

The ratio is what makes these places unusual

Plenty of cities contain a university. A university town is the narrower case where the institution is large relative to everything else, so that students and staff make up a substantial share of the resident population and the local economy is organised around them. Once that ratio passes a certain point, the institution stops being one employer among many and becomes the thing that sets the rhythm.

You can usually tell within an hour of arriving. Bookshops and photocopying, cheap food at odd hours, a bicycle population out of proportion to the town, noticeboards with room adverts, and a housing market whose prices make no sense against local wages are all symptoms of the same underlying arithmetic.

The pattern is worldwide but the form varies. Some universities are collegiate and physically woven into the streets, some occupy a single campus on the edge, and some were deliberately built in a small town in the twentieth century as regional development policy. The three produce quite different towns.

Term time and vacation are two different settlements

The academic year empties and refills the town on a schedule that is published a year ahead, and the swing can be large enough to change how the streets feel. In the long vacation, a place that spends most of the year noisy and crowded becomes quiet, parking becomes easy, and a proportion of the businesses that depend on student custom either close or cut their hours.

This is genuinely a trade rather than a straightforward better or worse. Out of term you get the architecture without the queues, and libraries, chapels and courtyards that are closed or busy during teaching are frequently open to visitors precisely because the students have gone. In term you get the atmosphere, the music, the talks and the sense of a working institution.

The transitions are the worst time to arrive without a booking. The weeks when students move in and out fill every hotel room in the area, because families come with them, and graduation ceremonies do the same thing again later in the year. These dates are published and are the single most useful thing to check before booking.

The institution owns a surprising amount of the place

Old universities in particular accumulated land, and centuries later that shows up as college gardens, sports grounds, farms on the edge of town and a great deal of student housing. Where the university is a major landowner, decisions about development are effectively made in two places, and the tension between town and institution is usually about exactly this.

It also decides what is publicly accessible. Some quadrangles, chapels and libraries are open on a defined basis, sometimes for a charge, sometimes only outside teaching hours, and sometimes not at all during examinations. The rules are institutional rather than municipal, which is why they can differ between two buildings on the same street.

Museums attached to universities are one of the genuine pleasures here. They were built as teaching collections rather than as attractions, so they are often free, idiosyncratic and arranged by discipline instead of by narrative, and they contain the sort of material a general museum would never display.

The economy this creates is narrow and slightly fragile

A town where a third of the customers are students has a food and drink scene calibrated to a student budget, which is why these places are frequently good value and why the range at the expensive end is thinner than the population would suggest. Landlords let by the academic year rather than by the calendar year, which distorts the rental market for everybody else.

Employment is concentrated too. The university and its associated hospitals or research institutes are often the largest employers by a wide margin, and any change in student numbers or funding is felt directly in shops that have nothing to do with education. Towns in this position tend to be acutely aware of it.

Against that, a large institution supplies things a town of that size would not otherwise have: a concert programme, a theatre, serious sports facilities, specialist medicine and a bookshop that survives on a customer base of readers. Much of it is open to anybody who turns up.

How to read one as a visitor

Look at where the students are not. The parts of a university town that have nothing to do with the institution are where its actual local character lives, and they are usually a short walk beyond the ring of student housing that surrounds the campus or the colleges.

Then look at what the university has done to the older town underneath it. The layout of a medieval trading settlement is often still there beneath the academic buildings, and the relationship between a market square, a river and a set of colleges tells the story of how one grew into the other.

And consider going to something. Public lecture series, chapel music, exhibitions and open seminars are common, frequently free, and rarely restricted to members, which makes them one of the more accessible ways to spend an evening somewhere you do not live.