bus outside the House of Blackheads, Riga, Latvia, 1920s

One of Riga best-known buildings, which was destroyed in WW2 and rebuilt after independence of Latvia from the Soviet Union. The Blackheads was apparently a union of young, unmarried merchants and ship captains in the Hansa cities, which chose St. Maurice to be their patron. St. Mauritius was an imaginary African black moor hence the name. No guess as to what the bus is.