I VISITED the Solovki Monastery on the White Sea in Russia last summer. The moment I walked through the gate, I felt I was on holy ground. Inside the icon-filled church, I had no doubt that this was a sacred place.

Yet it has a grim history. It was the first Soviet Gulag, a byword in suffering. Today, Solovki is being restored, and has become a focus of pilgrimage once again. Astonishingly, it kept its sense of religious purpose, despite the gruesome deeds that were executed there.

I have compared my response to Solovki with feelings I have sensed in other holy places. Just because a building has an ecclesiastical purpose, it is no guarantee that it exudes a spiritual atmosphere. In Britain, I visit many country churches, and my first impression is frequently based not on what I see, but on what I feel.

I have entered dreary buildings with small windows letting in cold autumnal light, and yet have sensed spiritual radiance inside. Conversely, I have stood in some airy, architecturally stunning buildings, and felt the place to be spiritually dead. It is difficult to understand what I am responding to. Possibly I am sensitive not to the building, but the ground on which it stands. Churches built on ancient, pre-Christian foundations, sited, so it is said, where forces of invisible earth energy cross.

It is a fanciful idea, but I know of dowsers who specialise in dowsing churches to locate the hidden energy forces under the floor; and the idea that buildings have "energies" that influence their occupants is both ancient and modern.

I have heard it suggested that stone absorbs prayer. The spiritually vibrant places are those with the longest history of the deepest prayer. It is a seemingly absurd notion, backed by neither science nor theology. It raises the question what prayer is. It is nothing like gravity or electricity, which have measurable properties.

If stones are capable of building up prayer-capital over centuries, one might suppose that old churches would "feel" more spiritual than new buildings. From my experience, this is not always the case.

Perhaps it is all a matter of expectation. If you know in advance that a particular site was once the scene of evil, it surely colours your response to it. That explanation does not, however, account for my response to Solovki. There, I sensed immediately that it was a holy place, despite its history as a Gulag. Perhaps present use is more important than past. Solovki has a new generation of monks, who offer a daily cycle of prayers.

The rationalist in me suggests that my reaction to a building could be determined by something as mundane as ambient temperature. A church with a good heating system is more welcoming than a cold, musty one. Standing physically chilled in a little-used country church, however, I have at times felt the spiritual warmth of a place.

Much, I am sure, depends on my mood, and how spiritually receptive I am at that moment. Nevertheless, on entering certain holy buildings, I sense something special, although I cannot describe exactly what it is.

Many people talk of feeling an atmosphere on entering certain buildings. Some places produce a shudder; others exude peace.

Of all the possible explanations,I like the theologically unsoundand scientifically unprovable one that buildings absorb the prayers offered in them. Whatever happens subsequently to those buildings, even if deconsecrated and desecrated, those prayers remain there for future generations.

That stones absorb prayer is an absurd and charming image; and one that perhaps contains a grain of metaphorical truth.

It is an idea that reminds me, as I stand surrounded by the walls of a sacred space, to add my prayers to those of history before I leave.

Ted Harrison is a writer and artist, and a former BBC correspondent.