Delicate works by artists from Fra Angelico to Leonardo to include loans from the Uffizi in Florence

The British Museum’s collection of Italian Renaissance drawings is so fragile that its masterpieces are exhibited only once in a generation.

Next summer a chance to see these delicate objects will finally come around, as the museum launches an exhibition, in partnership with the Uffizi in Florence, of works on paper by artists from Fra Angelico to Leonardo.

The 100 or so works will span the period 1400-1510 and artists including Jacopo and Gentile Bellini, Botticelli, Filippo Lippi, Mantegna, Michelangelo and Raphael.

About half of the works will come from Florence, and some have never been shown in the UK before. Bringing the drawings from Florence together with those from London, said British Museum director Neil MacGregor, will “together allow a different reading of draughtsmanship from the period. It will allow a new engagement with this part of the Italian Renaissance.”

In typical British Museum style, the message is “only connect”; for the museum will at the same time mount an exhibition of West African sculpture of the same period. Works from the kingdom of Ife – a powerful, cosmopolitan city state in what is now Nigeria that flourished from the 12th to the 15th centuries – will form the focus of an exhibition for the first time outside Africa.

“They are works of absolutely comparable quality [to the Renaissance drawings],” said MacGregor of the strikingly finely worked, naturalistic sculptures.

The exhibitions together form a counterpoint to the blockbuster Moctezuma exhibition, opening this autumn, which will also focus on the early 16th century – this time on the last Aztec emperor before Spanish conquest. MacGregor said Mexican colleagues had been “astonishingly generous” in loans to the exhibition, which include the ceremonial throne-cum-altar of Moctezuma.

Alongside elaborate Aztec skulls, the exhibition will also show a selection of contemporary Mexican skulls created for the Day of the Dead, the festival energetically celebrated in Mexico on 1 November. The British Museum will also celebrate the feast, and, according to MacGregor, “large quantities of sugar skulls, the delicacy of the Day of the Dead, are already on order”.

MacGregor, launching the museum’s annual review, reported on the British Museum’s next big step: its “north-west development”, a 11,000 sq metre exhibition space and conservation centre.

Two-thirds of the funds for the £135m extension are secured, and, according to British Museum chair Niall FitzGerald, the museum is “shovel-ready” to start work on building, pending trustees’ go-ahead and planning permission from Camden council, a decision on which is expected later this month. English Heritage, said a museum spokeswoman, are fully backing the plans for the extension.

The new space, designed by Graham Stirk of Rogers Stirk Harbour & Partners, Sir Richard Rogers’s practice, is planned as a replacement for the reading room in the museum’s Great Court as the venue for large-scale exhibitions such as those recently devoted to Hadrian and Shah Abbas. Permission to use the reading room as a venue for exhibition expires in 2012 and, warned FitzGerald: “If we don’t have another space for our exhibitions that would be a catastrophe.”

The government has pledged £22.5m for the development; about £30m will come from the museum’s reserves and the balance, MacGregor was “hopeful and confident”, is being found from private donors.MacGregor said that a key challenge for the museum was getting its collection out on the road. In the last financial year, 2,500 objects from the museum were seen in other UK locations.

Transporting objects, he said, was “technically safe – the limits are now ones of resources and making sure there are places that can receive them”.

Developing the museum’s online facilities was also crucial. “By the end of this year there will be 2m objects online – well ahead of any major institution in the world,” said MacGregor. “Making available free digital downloads of the highest possible quality is the natural corollary of free entry to the museum.”

It was a year of growth for the institution, with visitor figures for 2008 at 5.93m, making it the most popular visitor attraction in the UK.

A number of important gifts had been made to the museum, and new galleries created for the matchless Percival David collection of Chinese art, which has been lent to the museum in perpetuity. It is, said MacGregor, the most important addition to the museum collection since the Sutton Hoo treasure in 1942.

The world around 1500: connecting the British Museum’s exhibitions

In 1492, Christopher Columbus sails to the Americas.

In 1498, Vasco da Gama reaches India after rounding the Cape of Good Hope.

In 1492, the last Muslim ruler of Granada, Boabdilm, surrenders to Ferdinand and Isabella of Spain. In 1499, forced baptisms begin.

In 1502, Moctezuma becomes ruler of the Aztec empire (Aztec mask below); under him it reaches its largest size. In 1519, he and Cortés meet.

By the end of the 15th century, the kingdom of Ife in modern Nigeria begins to give way to Benin as a wealthy west African political and artistic centre.

In the early 16th century Benin sends an ambassador to Portugal; Portuguese missionaries are sent to Benin.

Somewhere between 1503 and 1507, Leonardo paints the Mona Lisa.

In about 1507, Raphael paints St Catherine of Alexandria, now in the National Gallery.

In 1513, Machiavelli writes The Prince.

In 1516, Rafael Perestrello, a cousin of Christopher Columbus, becomes the first European explorer to land on the southern coast of mainland China. The following year, the Portuguese send an expedition to try to set up trade relations with China in Guangzhou.

In the early 16th century, the Mughal empire begins its rise.

In 1503, Henry VII obtains a papal dispensation allowing his son Henry to marry his widowed daughter-in-law, Catherine of Aragon.