The Stone Town is the product of at least three centuries of continuous settlement, but it was only from 1830 that Zanzibar took on a wholly urban character and that stone buildings were built in significant numbers. Until that time, the majority of houses were made of mud and wattle, and roofed with palm leaf thatch. Very few large-scale structures could be distinguished, besides the Fort and a few small mosques.
At the beginning of the nineteenth century, the town occupied only the north-eastern portion of the peninsula, extending from Shangani Point toward the creek's narrowest crossing at Darajani. After the Omani Sultan's permanent move to the island in 1832, the Stone Town quickly expanded during the middle of the century, filling in the areas of upper Sokomuhogo, Forodhani, Kajificheni, and Kiponda. The Omanis erected palaces and residences along and behind the sea front, and tradesmen from the Indian sub-continent built up the bazaar streets with shop-front houses, and sea-faring merchants built houses, sheds, and warehouses near the waterfront. After 1850, stone buildings spread further and began to extend north into Malindi, south into the lower portion of Sokomuhogo, and east to Mkunazini, areas which up to this time had been mostly occupied by mud buildings. As contact with western trading markets increased, particularly once the Suez Canal opened in 1869, and later with the establishment of the British administration in 1890, specialised structures - larger civic buildings in particular - began to appear. The building up of the Stone Town was more or less completed and the present limits defined by the first quarter of the twentieth century: the new port area to the north had been reclaimed, the area south of Shangani built up, the European garden suburb of Vuga laid out, and the programme to fill the creek bordering the peninsula to the east gradually put into effect.
Thus, within the relatively short span of one hundred and fifty years, the confluence of several distinct cultures and the island's intense cosmopolitan development produced the rich and diverse architectural heritage we see today. In some cases, the diversity of the original imports is still evident in different sections of town; in others, the borrowing and adaptation of forms from other contexts produced a cross-fertilisation of different building traditions. In yet other cases, buildings were gradually transformed over time as newcomers adapted existing structures to their tastes and preferences, thus determining a further hybridisation of forms. This variety produced the diverse spaces and surprising contrasts of the Zanzibar townscape, where pedestrians move from the imposing row of sea front structures to the crowded and lively atmosphere of the Indian bazaars, and the quiet, intimate spaces of the narrower residential streets. Thus, although the different forms and building types and their origins - African, Arab, Indian, or European - can be recognised, it is the synthesis of these cultures and influences that creates Zanzibar's unique urban and architectural environment.
The old Customs House is strategically located along Zanzibar’s northern seafront, the most visible and significant public open space in the town. It was built as a family house during the reign of Sultan Majid Bin Said (1856-1870) as one in a group of buildings owned by the Busaidis, a branch of the ruling family. It remained in the Busaidi family until 1928, when the Customs authority offices were moved here from a nearby shed (thence its name). From 1980 until 1987 the building housed the income tax department. Afterwards it remained largely empty until it was entrusted to the Ministry of Water, Construction, Lands and Environment (MWCELE) in 1992. The first phase of the building’s restoration took place between 1993 and 1996, in coordination with the Stone Town Conservation and Development Authority (STCDA) with Funds-in-Trust made available by the Government of Italy to UNESCO. Subsequently, restoration work was taken over by AKTC and completed in 1999.
The Customs House is a three-storey structure arranged around a large central courtyard, with two towers flanking a second rear courtyard. Rectangular in plan and covering a total surface of 1,200 square metres, the structure has a three-bay façade, with narrower outer bays topped by gabled pediments. Originally, the façade was relatively plain, with regular fenestration and horizontal string-courses. In 1896, an imposing three-storey cast iron balcony was added to the front of the building. Removed in 1989, it was reinstated in 1998 as part of the restoration work carried out by AKTC. Inside, the central courtyard is surrounded by a ground-floor arcade and loggias above. All three floors are lined with long and narrow rooms overlooking the sea and the rooftops of the town behind.
The construction systems reflect traditional building practices in East Africa: coral masonry laid in lime mortar, wall surfaces covered with coral lime-based plaster, coral rubble ceilings supported by exposed timber joists, and a flat roof with a crenellated parapet. The width of the rooms is determined by the span of the structural joists, an average of four metres.
The Customs House, at the time restoration work started, retained most of its original features, including the balcony components, which, although dismantled, were stored in the building. Various alterations however had taken place over the course of the building’s life span. These coincided mostly with the building’s changes in use, but started already in the late nineteenth century while it was still a residential building. These consisted in the addition of the cast iron balcony, modification of the flat roof with the construction of a pitched corrugated iron roof, and various internal modifications. When, in 1928, the building became the office of the Customs and Excise Department, there occurred numerous transformations of the interior spaces, including partitioning, enlargement of structural arches, bricking up of the upper balconies, new stairs and toilets. Additional interior transformations took place in the 1980s, when the top floor was subdivided to create two separate apartments assigned to government tenants.
Years of improper maintenance and neglect had left the building looking decayed and derelict, but its structural condition was relatively stable, with the exception of the building’s southwest tower. The main structural concerns were the collapse of the southwest tower’s flat roof and severe cracking along the exterior vertical walls. The collapse was caused by the failure of the undersized beams, which were too weak to support the roof. The failure of the flat roof, in turn, allowed water to infiltrate the walls over a long period of time, which eventually resulted in the large cracks and outward movement of the walls. Other problems noted in the building were poor bonding and a high proportion of voids within the structural walls, exacerbated by the fact that the walls themselves were poorly tied together, a fact that had considerably weakened the structure over time. Extensive deterioration also affected plaster surfaces, floor slabs (wet rot and insect attack of the joists infiltrated by water), the pitched roof, as well as joinery and ironmongery throughout the building. Finally, there was a need to completely substitute electrical, water, plumbing and drainage installations.
The approach to the repairs and interventions carried out by the UNESCO and AKTC teams can be summarised as follows: a) to respect the existing fabric including alterations made to the building during its life span. Only in exceptional cases, where evidence of the original configuration still existed, was the old configuration reinstated; b) to conserve rather than replace any salvageable component of the building; c) to improve through new interventions the quality of the fabric in cases where intrinsic structural faults could be detected (e.g. the bond between upright walls and floor slabs); d) to fit the proposed new uses around the original fabric so as to avoid disruption, loss or disfigurement of the building’s traditional features. In line with this approach, the interventions aimed at stabilising and preserving the original building components, eliminating disruptive accretions or modifications no longer justified, and re-establishing the original finishes and well-documented components that had been demolished or removed in recent years, such as the cast iron balcony.
In conjunction with the conservation programme for the structure, a scheme for its adaptive use was finalised, based on the premise that there is no better way to guarantee long-term preservation of a building than to ensure its continued use. Following extensive consultations locally, a building use program was identified that would not conflict with the structure’s architectural qualities and that would generate the income needed to maintain the building in the long term. A not-for-profit conservation centre, including a conservation laboratory (a facility hitherto not available in Zanzibar), became the first tenant of the restored structure. The rest of the building is leased to private offices. The building has been occupied since the early 2000s and has managed to meet the cost of its recurrent maintenance and operation.
The implementation modalities of the restoration works are of special relevance, as the building works process incorporated a significant training component. The works were in fact split into a series of separate components and implemented as works carried out either by experienced local craftsmen recruited directly, by the trainees, or by sub-contracting discrete packages to specialised contractors, such as joinery repairs and replacement of electrical installations. The combination of these different implementation modalities made it possible to maintain control and flexibility at all stages. Further, it enabled the project team to ensure good quality in the work performed, reduce and monitor costs, and closely integrate the training component into the overall building conservation process, thus creating a new generation of skilled artisans specialised in traditional crafts and restoration.