Zanzibar buildings old and new: what they are made of and what state they are in

This guide covers five Zanzibar buildings: the House of Wonders, the Old Dispensary, the Old Fort, Christ Church Cathedral and the Burj Zanzibar tower project. UNESCO names the first four among the monuments of Stone Town. It describes the town's buildings as made mainly of coralline ragstone and mangrove timber set in thick lime mortar, then plastered and lime-washed (UNESCO World Heritage Centre, checked on 13 November 2026). Old-town style is in our guide to Zanzibar architecture, and Swahili building elements in the guide to Swahili architecture.

House of Wonders: iron columns, high ceilings and a collapse

Sultan Barghash built the House of Wonders, or Beit al-Ajaib, in 1883 as a ceremonial palace on the waterfront. A study by Longair and co-authors describes wide verandas on cast-iron columns and very high ceilings. The outer galleries were set on iron pillars forged in England. Its chandeliers ran on an electric generator, the first in sub-Saharan Africa, and it had East Africa's first lift (Longair and co-authors, checked on 13 November 2026).

The clock tower followed in 1897, after the British bombardment of 1896, and in 1913 the palace became the Secretariat of the British colonial government. It became the National Museum of Zanzibar in the early 2000s (same study, checked on 13 November 2026).

The 2020 collapse and after

On 25 December 2020 the House of Wonders partly collapsed, clock tower included, and two people⁠¹ inside were killed. An earlier collapse on 2 December 2012 had already weakened the structure. Oman's late Sultan Qaboos had left money in his will for its restoration. At the time of the collapse, though, Oman's heritage ministry said its work on the building had not yet begun (same study, checked on 13 November 2026).

In January 2021 the Tanzanian embassy in Israel reported a possible restoration by the Zanzibar government and the UNESCO World Heritage Centre. The same page describes the collapsed section as undergoing renovation funded by Oman's Ministry of Heritage and Tourism (embassy page, checked on 13 November 2026). The Zamani Project recorded the palace in 3D in 2019 and, after the collapse, in 2021 (Zamani Project, checked on 13 November 2026).

A UNESCO World Heritage Centre advisory mission visited the House of Wonders on 29 January 2025. The works are managed by Oman's Ministry of Heritage and Tourism, and the mission reported that “the works are progressing carefully”. Shoring and scaffolding were complete, and cracks and movements of the structure were being monitored. The foundations were being dug out and reinforced in three⁠⁹ stages of alternating areas, with reinforcement at about 40%⁠⁹. The project plan foresaw completion towards the end of 2026 (UNESCO mission report, checked on 13 November 2026).

The report adds that the marble floor tiles had been lifted, restored where possible and stored for reuse. A large part of the first-floor ring beams has to be rebuilt, partly because the I-sections and railway tracks encased in them have corroded. New cast-iron columns were being ordered to replace broken veranda columns. The repair mortar, PLC, is hydraulic lime, sand, water and a little white Portland cement, grouted into the existing foundations (same report, checked on 13 November 2026). We could not find a later report on the works in official sources on 13 November 2026.

What we check before work on an old structure

Before we price work on an existing building in Zanzibar, we measure it, draw what stands today and photograph each room. Where part of a structure has failed, no one works below it until a structural engineer has inspected it.

Old Dispensary: a building raised in stages

A brochure of the Aga Khan Trust for Culture (AKTC) dates the foundation stone, laid for a planned hospital, to July 1887. Following local practice, the foundations were left for two years⁠⁴ to weather and consolidate. Meanwhile a Bombay firm oversaw the making of the joinery. Masons from Kutch arrived in 1890; after a pause from 1891, the building was completed in early 1894 (AKTC, checked on 13 November 2026).

Longair and co-authors describe it as combining Indian and European neo-classical ornamentation with local coral rag and lime construction (Longair and co-authors, checked on 13 November 2026). AKTC restored the building between 1994 and 1996, says an Aga Khan Development Network release. In April 2022 the Stone Town conservation authority approved the design for its conversion. A year later, in April 2023, it opened as the first Aga Khan Polyclinic of the Aga Khan Health Service in Tanzania (AKDN, checked on 13 November 2026).

Lessons for a phased build

On a hotel built in phases, as part of our hotel construction in Zanzibar, the drawings and photo record of each stage stay in one file. If work pauses, the next crew starts from that record.

If a building in Zanzibar changes use, we prepare the drawings the authority asks for and wait for its decision. The steps are in our guide to building permits in Zanzibar.

Zanzibar buildings and our hotel work

Old Fort: a fort that took in church remains

Tim Power and Mark Horton report on excavations of the fort's western courtyard in 2017 and 2018. They found the site occupied without a break since the eleventh century AD. A Portuguese trading post and an Augustinian mission followed in the sixteenth century (Proceedings of the Seminar for Arabian Studies, checked on 13 November 2026).

At the end of the seventeenth century the Yaʿrubids of Oman built the church remains into a square-plan fort. In the nineteenth century the Old Fort was doubled in size on the order of Sayyid Saʿīd (Power and Horton, checked on 13 November 2026). Of the Zanzibar buildings in this guide, the fort is the oldest.

Old walls on a new plot

Old foundations or a ruined wall on a client's plot go on the survey drawing with measurements and photographs. Whether they stay is agreed with you before design starts. If digging uncovers old masonry, we stop that part of the work and tell you.

Christ Church Cathedral: a building once in danger of collapse

British missionaries built Christ Church Cathedral in 1879 on the site of East Africa's last permanent slave market, World Monuments Fund writes. The fund notes that “Zanzibar's tropical climate took its toll on the building”. By the time World Monuments Fund Britain became involved, the cathedral was in danger of collapse. In 2013 the Anglican Diocese of Zanzibar and the Zanzibar government asked the fund for help. World Monuments Fund Britain then received a European Union grant to repair the cathedral (World Monuments Fund, checked on 13 November 2026).

Who must approve a repair

On a repair job we ask early who has to agree to the work besides you, for example a trust or a government office. The scope and repair method are set out in writing before anyone starts on site, as part of our renovation work in Zanzibar.

New Zanzibar buildings: a timber tower project

For the Burj Zanzibar tower project, structural engineer Knippers Helbig describes a 95-metre⁠¹⁰ high-rise in hybrid timber, a pilot project that it says will become Africa's tallest hybrid timber building. A central reinforced concrete core, running from the top down to the foundations, braces the tower. Cross-laminated timber (CLT) floors pass sideways loads to the core, and CLT walls and floors on GL24 columns and beams carry the vertical load. The page names OMT architects and Birk Heilmeyer und Frenzel Architekten as architects and gives no construction status (Knippers Helbig, checked on 13 November 2026).

Who designs and who checks

With a hotel brief, we first ask who designs the building and who checks its structure, and we put both names on the drawings we send you. If you already work with an architect, we also ask for the structural drawings before we prepare an estimate.