Take two apartments in Dublin 4: one is in Brookfield, a 1960s block on Anglesea Road; the other is in the early 1990s-built Sweepstakes development, also in Ballsbridge. Both are around 900 sq ft but while the Brookfield apartment is on the market for £250,000, the Sweepstakes one can expect to fetch £350,000.

A 1979 apartment in the quiet, secluded Milltown Grove, Dundrum - at 1,055 sq ft as big as the average three-bed semi - is on sale for £295,000. In Dublin 8 a smaller apartment at the newly built Warehouse development on Clanbrassil Street will cost you £5,000 more.

Choosing between an old apartment and a new one can be like choosing between a station wagon and a sports car - the old ones have fewer frills and gimmicks but they tend to be built for comfort with far more room to manoeuvre. Older apartments tend to be better value per square foot but the trade off is that they tend to be more basic and less sexy than their shiny new counterparts. The first apartments were built in the late 1950s but the real beginnings of apartment life - the year 1 AL - can probably be pinpointed to circa 1970. We are now in the year 30 AL and there are many examples of the earlier model dotted around the inner suburbs.

I once viewed a mid-1970s block in Ranelagh with a friend who had been apartment hunting for the best part of a year. The estate agent's blurb said this two-bed apartment was "in need of some refurbishment" but neglected to mention that only the brave or the desperate could live with the decor. Untouched since the previous tenant had moved in around 1976 - its loud-patterned carpet vied with zigzag wallpaper which clashed with the lime velour sofa included in the sale.

My friend had seen so many shiny, pong-free new apartments that his first reaction, and mine, was that transforming it into a minimalist bachelor pad would require trojan work. But then he started to mull over the pros and cons. The estate agent wasn't fibbing when he said that this apartment had lots of potential. There was tons of space in the main bedroom for his computer and CD system. He could fit two sofas in the livingroom as well as a sizeable table and chairs. Best of all he would be near both the city centre and the bright lights of downtown Ranelagh. By the end of that week he had decided to put in an offer. Tragically, by the time he'd finished ruminating the flat had been sold to someone else - someone who had spotted its potential straight away.

The reason older apartments tend to be more spacious than modern ones is that they were built for a different market. According to David Lewis, of Sherry FitzGerald, those lured by apartment life in the 1970s were mainly older people who wanted to scale down from the burdens of a house to a smaller, although not poky, more manageable space: "Apartments in those days often didn't have the extras like en suites, security parking or security gates and perhaps not as much would have been spent on the communal grounds but they tend to have internal space. They are still popular with older people who are not looking for all mod cons and prefer to live in a mature location."

How well older apartment blocks have withstood the ravages of time depends largely on how their management companies have looked after them over the years. According to David Lewis, some of the better-managed blocks have undergone several revamps since they were built: "Some blocks become a little dated where there is no sinking fund. A sinking fund is where, for example, the annual service fee is £500, and the management company spends £350 and keeps the rest in a fund which builds up over time. Where apartment blocks don't have this fund, the residents often have to shell out large amounts of money in special levies when something needs to be done.

"Typically the service charge for a good block will be £800 to £1,000 a year if it is to be well maintained with attention paid to lifts, lights and the communal area. You are better off paying these kinds of service charges if apartments are to be properly looked after, which will add to the value of your property in the long run."

The price of older, mainly suburban, apartments depends largely on their size and location. Typically prices start at about £160,000 for a one-bed, £240,000 for a two-bed and £300,000 for a threebed. James Pike of O'Mahony Pike Architects has been involved in apartment building since the 1970s. He sees a trend back to building lower density apartment blocks.

"In the tax incentive years of the late 1980s and early 1990s, some of the inner city apartments were built with long, hotel-like corridors and some had relatively few lifts and staircases per number of apartments. They were in many cases providing flats for the original bedsit market that were smaller, more affordable and more viable for the single person or young couple.

"The corporation has made that more difficult. It's going back to the way it was in the 1970s with smaller numbers of flats but more of them now have atriums and more attractive access."

Pike believes there is an untapped market for more spacious inner city apartments: "There are very few flats of a larger size in the inner city. It's a pity because there are people in the market for a flat of 1,000 sq ft to 1,200 sq ft, even if it is only a two-bed. If their house was 1,800 sq ft or more, they won't want to shrink down to under 1,000 sq ft. A number of current developers are missing out on some of that potential market."