Three hundred years ago antiquaries were at the forefront of modernity. This odd paradox is captured in the Royal Academy’s exhibition marking the tercentenary of the Society of Antiquaries. The society is therefore the same age as Britain as a unitary state. This bravely unfashionable exhibition shows how the work of these enthusiastic amateurs — much mocked, then as now — contributed to the creation of a national sense of the past.

The first room is dominated by a 12-metre scroll, on which the genealogy of Britain’s monarchs was traced from Adam to Charles II. This magnificent object was given to the society by a Fellow in 1803; a transfer which symbolises the shift from an age when wonderous objects of the past were seen as baubles and appendages of princely power, to one where they were, in some sense, national heritage.

The project of the early antiquaries of the 16th and 17th century was to preserve the remains of a past made fragile by the dissolution of the monasteries and the Civil War. Without a knowledge of their own past, said William Camden, one of earliest and most important antiquaries, men risked becoming “strangers in their own country”. The 17th-century antiquaries were motivated also by the same Baconian urge for collection and examination that inspired the great scientists of the period — and indeed antiquarians crowded the Royal Society for much of its first few decades, until they were squeezed out by the austerely mathematical Isaac Newton.

Antiquarianism was not a single-minded project. The cabinets of curiosities collected by 17th-century virtuosi, just as much those collected by earlier princes, were full of objects whose rareness and variety was their own justification. John Bargrave’s collection contains such treasures as a “finger of a Frenchman” and a lump of masonry chiselled from the Arch of Titus in Rome.

But the paintings of British buildings the society collected reveal their urge to amass and preserve for the nation. One of the finest is a 1616 panel portraying old St Paul’s; the image is preserved even if the cathedral could not be. After the establishment of the society, more concerted efforts were made to save threatened monuments. We see the ill-fated efforts of William Stukeley to protect Waltham Cross, marking a resting place of the funeral cortège of Queen Eleanor in 1290, from 18th-century traffic.

Many of the most fascinating objects found by these early antiquaries came from graves. The Rev Bryan Faussett opened about 750 ancient graves in the mid-18th century and made some wonderful finds. But the activity had an undeniable element of ghoulishness, skewered by Rowlandson’s 1816 cartoon of a pack of antiquaries slavering over the opening of a majestic tomb (probably that of Edward I, which was opened and examined in 1774).

In the 19th century, as the Industrial Revolution gathered pace, many fine objects were unearthed by the constant churn of new roads, railways and suburbs, but many others were threatened. Antiquaries went to great lengths to safeguard these fragments of the past. In doing so, they made these buildings and artefacts reference points for a national story that the high Victorian age came to venerate; both Walter Scott, at start of this period, and William Morris, at its end, were Fellows of the society.

The exhibition closes with Stonehenge, the site that most obviously and awe-inspiringly declares the antiquity of civilisation in Britain. The 17th and 18th-century antiquaries debated whether it had been built by Romans, Druids or the Danes. These speculations, in a series of detailed and delicately illustrated works, show how such sites became central to the British idea of ourselves; and why Making History is of more than just antiquarian interest.

Making History: Antiquaries in Britain 1707-2007, closes on December 2. Royal Academy, London W1J 0BD 020 7300 8000