[1] He was the London-born son of Sir Jacob Jacobsen, a north German merchant, of a family closely involved with the Hanseatic League, and their London base, the Steelyard.
[2] In the period 1726–9 Jacobsen rebuilt East India House in the Doric order, which took on the form it presented for the rest of the 18th century.
[2][3][4] In 1731 Jacobsen was unsuccessful in submitting a plan to the Bank of England, for building work that was carried out to a design by George Sampson.
[1][2] After a falling-out with Jacobsen in 1742, Thomas Coram, the hospital's founder, failed to be re-elected to its General Committee.
[1] His plans for Trinity College, Dublin's West Front and Parliament Square were carried out in the 1750s by Henry Keene and John Sanderson (died 1774) with Hugh Darley acting as superintendent.