Rented St. Agnieten Tooren from the city for 12 years

On December 5, 1693, Leeuwenhoek and Paul Durven rented St. Agnieten Toren (also spelled toorn) from the city for 12 years for 12 guilders per year, according to the city's Consentboek (permit or license book) for 1664-1794.

On early maps, the tower appears as a bastion that juts into the singel, as did the other towers on the southern and western sections of the singel. By the time Leeuwenhoek rented it, it was enclosed and had a pointed roof, according to the Kaart Figuratief (detail top right; click to enlarge; north is left). The tower was at one end of a garden that ran east along the singel toward the city's Oostpoort. At the other end of the garden, about 75 yards (68 meters) away, was Paul Durven's family home on Oosteinde.

Paul's father Pieter Gerrits had rented St. Agnieten from the city in successive multi-year leases, 24 gl yearly, from 1658 until his death, when the lease was picked up by Paul, who 35 years later co-signed with Leeuwenhoek. Presumably, Leeuwenhoek paid the rent and Durven kept his name on it so no one other than he could rent it after the 12 years.

Leeuwenhoek rented the tower a month before his second wife died and three weeks before he sold his garden outside the city's western wall. He doesn't mention this tower in his letters, so we don't know what Leeuwenhoek did there. No other document exists to explain why he rented it.

Perhaps he used the tower to store some of the things his wife had accumulated, to store leftover inventory from his fabric business, to do his research and writing in peace, or to meet friends for socializing or scientific colleagues for consultation without disturbing his household.