There was atime when the world of antique maps was considered to be old-fashioned and staid, the preserve of rural squires obsessively collecting 16th-18th century maps of their own county. Today this picture has been transformed by the recognition of maps not just as important primary historical sources but also objects of great beauty. Map collectors nowadays are much younger people, with interests in travel and history, who appreciate the wonderful stories that maps tell.

This growing demand for the limited supply of antiquarian maps is reflected in the rapid increase in value of the more sought-after pieces. That said, it has been noted by the savvy investor that important antique maps are still remarkably undervalued considering their rarity, beauty and significance. The map market, dominated by collectors rather than speculators, also benefits from having remained virtually immune to the economic fluctuations and recessions that commonly affect art markets.

When considering investing in antique maps the first crucial question is, of course, maps of where? Map collections are as varied as the collectors themselves; some focus on a particular period such as the Dutch Golden Age of Cartography (1570-1700), or on a specific map-maker such as Abraham Ortelius. Others single-mindedly collect a certain feature such as maps depicting California or Korea as an island or just pieces that have a strong personal resonance.

Whatever the emphasis of your collection the single most important factor is to only buy what you love! The joy of map collecting is that there is a wonderful diversity of subject, period and price. Whatever you acquire, your investment if hung on the wall will tell a multitude of stories and give you pleasure every time you look at it but if you decide to sell it, it will appeal to its next owner the same way.

Having said the above, there are undoubtedly areas of map collecting that have risen faster than others and this is usually driven by the economic strength of the area depicted. Some regions such as North America have always been rich in enthusiastic investors, which has ensured that they always fetched premium prices. The areas of greatest localised growth have been in the Far East reflecting the Chinese boom. But where the market has risen the most in recent years is maps printed in the 20th Century, as they can surprisingly often be rarer than pieces several hundred years older, the result of printing on less durable paper.

There are a number of other physical factors as well as the area shown which affect the value of maps. Age and rarity are often synonymous as basically the older a map, the less likely it is to survive. Condition is a crucial factor in assessing the current and likely future value of any piece.

The most important piece of advice for the new map buyer is to shamelessly plunder the knowledge of experts to inform their buying options. Most map dealers are only too delighted to share their expertise and they should also stand behind any description of a purchased map backed up with a written guarantee of authenticity.

Philip Curtis is director of The Map House. Their upcoming exhibition War Map: Pictorial Conflict Maps 1900-1950 will be on show from 23 September - 18 November. The exhibition is accompanied by a book published by Sifton, Praed & Co on 6th October.