The Mole of Argier was the main concern of the Diary, beginning 1 February 1661/62 http://www.pepysdiary.com/diary/1662/02/01/
Pedro. on Wed 2 Feb 2005, 9:20 am | Link
"mole of Argier”
The inner harbour was begun in 1518 by Khair-ad-Din Barbarossa (see History, below), who, to accommodate his pirate vessels, caused the island on which was Fort Penon to be connected with the mainland by a mole. The lighthouse which occupies the site of Fort Penon was built in 1544.
Argier (Algier): http://www.pepysdiary.com/encyclopedia/3088/
Chris Squire • Link
‘mole, n.2 . . Middle French mole in uses corresponding to sense 2 is probably not immediately < Latin, but, as indicated by the gender, probably arises ultimately from Byzantine Greek μῶλος , μόλος (6th cent.; < classical Latin mōlēs ), which was probably borrowed into Italian as molo (a1313;
. . 2. A massive structure, esp. of stone, serving as a pier, breakwater, or causeway. Also: the area of water bounded by or contained within such a structure, esp. forming a harbour or port.
1545 in Acts Privy Council 8 Sept. (1890) I. 241 Letters to Boloyne for the making of a Jettye or Mole.
. . 1632 W. Lithgow Totall Disc. Trav. x. 448 A French ship‥that was lying in the Mould.
1641 L. Roberts Treasure of Traffike in J. R. McCulloch Early Eng. Tracts Comm. (1952) ii. 100 Hee erected a watch-Tower with a strong mould to preserve the ships that anchor there from the violence of all weathers.
. . 1727 A. Hamilton New Acct. E. Indies I. vi. 53 It has‥a pretty good Mould, or Bason, for the Easterly [monsoons].’ [OED]
A model mole - Genoa
The Genoese dominated many of the main shipping and trading routes in the Mediterranean (including the slave trade), and Genoa was well-known and respected as a seafaring power. In this late fifteenth century Italian (?) illustration, merchant ships enter and depart from Genoa's harbors. http://home.gwu.edu/~jhsy/genoa-harbor.jpg Note the mole and watchtower that had had long been admired as a model way to provide and secure an anchorage for such a port.
The Mole of Tangier (not Argier) was a main concern of the Diary, Pepys having served beginning 1 December 1662 on the Tangier Committee, that supervised the English colony there. After the Tangier Regiment took possession of Tangier, the English planned to improve the harbour by building a mole, which would reach 1,436 feet long and cost £340,000 before its demolition. The improved harbour was to be six hundred yards long, thirty feet deep at low tide, and capable of keeping out the roughest of seas. Work began on the fortified harbour at the end of November, 1662, and work on the Mole in August, 1663. Each redoubt had four hundred men guarding the excavation site, while to the front balls of spikes, stakes and piles of gunpowder-and-stone mix, which acted as basic landmines, were laid. The work continued for some years under a succession of Governors. With an improved harbour the town would have played the same role that Gibraltar later played in British naval strategy. https://en.wikipedia.org/wiki/English_Tangier#E...
Chart showing the number of references in each month of the diary’s entries.