A recent model of the Russian design of the wrought-iron structure in lattice form which still forms the basis of the rotunda dome today, despite being buckled by an earthquake in 1927.
A photo from the 1880s, showing one of the two mortar shells being laid over the wrought-iron structure. The imposition of massive pillars and store rooms reduced the diameter of the rotunda from 30 to 20 meters.
A photo from 1885 showing the timber boarding being laid over the inner mortar shell. The second mortar shell covered the timber. The process extended in stages.
The final lead covering on the dome. The photo shows the staircase leading to the balcony of the rotundra, taken in the period as the final scaffolding was being removed.
