At the end of the 19th and the beginning of the 20th centuries, on Kronverksky Prospekt, near the Nikolaevsky Bridge (as the Lieutenant Schmidt Bridge was called until 1918) and the Tuchkov Bridge, three identical toilets were built by order of the wealthy merchant Alexandrov, who owned the market on Kronverkskaya Street. They were designed by architect A. I. Zazersky as small mansions with towers, spires, and patterned brickwork — like miniature fairy-tale castles.
One of these remarkable toilets existed until 1965 and was demolished during the construction of the Gorkovskaya metro station. According to the memories of longtime residents, it had four sections — men's, women's, girls', and boys' (as indicated by enamel signs), and also featured a large niche-loggia where people waiting for the tram could shelter from bad weather. In a similar toilet near the Lieutenant Schmidt Bridge, at the end of the last century, a "Pirozhkovaya" (a pie shop) opened, and in the early 2000s, a café called "Taverna" was located there.
The construction was approved by the Duma on February 20, 1904; 15,000 rubles were allocated from the remaining credit for the construction of the Troitsky Bridge embankment. The project author and responsible engineer for the construction was civil engineer A. I. Zazersky. The construction was overseen by the city administration. The work was awarded by tender to contractor Kursanov. The building was accepted on November 15, 1906.
The first written mention of this legendary toilet was probably left by Mikhail Kuraev. On behalf of one of his less sympathetic characters, he writes:
"...right here nearby, at the tram stop, a luxurious public latrine on the corner of Gorky and Kirov streets.

By the way, the latrine is famous, shrouded in legend. It was built in the form of a villa, with flourishes, a tower, spires, patterned brickwork, God knows what! A castle from a German fairy tale. And the story goes like this. On the spot where we are sitting, there was an amusement garden, owned by the owner of the Central Market, Alexandrov. He was rich beyond belief — well, if he donated a tuberculosis hospital with all the equipment to the city at his own expense as charity, it still stands, we get fluorography there... You know, the red house to the left before the Kamennoostrovsky Bridge. At the end of Kirov Street. Alexandrov was considered a millionaire. And they said he took a fancy to a noble lady, say, a baroness. At first, she giggled and gave hope, accepted his courtship, but when it came to the point — no way! I don’t know how he pursued and persuaded her, not a small-time merchant, not in shiny boots, a capitalist, manners, cars, Europe!.. But she wouldn’t give in, period! They had a decisive conversation, she told him straight — man! You are a man, she said, and I am a baroness! And that was the whole conversation! A handshake, please, but only up to here, and no further... Mr. Alexandrov was left empty-handed. And interestingly, the lady was not so inaccessible after all, and that made it especially painful for him. He took revenge. She lived in a house at the beginning of the avenue, next to the Witte mansion, later the Institute for the Protection of Childhood was there, with windows facing the corner of Kamennoostrovsky and Kronverksky as it was then. The suitor turned to the city authorities: 'Caring for public health, I can build a public toilet in the People's House garden, a sort of latrine, at my own expense.' The city fathers, as the city council was called then, gratefully accepted the gift, a necessary facility, and a busy location. And the project dazzled with luxury — neither a castle nor a terem (traditional Russian towered house)... And this 'castle' was an exact copy of the country villa of that very baroness, inaccessible to successful commoners. So enjoy how any city resident uses your hospitality!
Well, she, of course, immediately moved out, changed apartments, settled near the Nikolaevsky Bridge, the Lieutenant Schmidt Bridge. And he had a latrine under her windows there too! Though simpler. She, poor thing, fled to the other side of Vasilyevsky Island, near the Tuchkov Bridge, and he had a 'public villa' under her windows there as well..."
After Kuraev, many repeated the story about merchant Alexandrov and the "baroness," almost verbatim. Igor Bogdanov writes: "At the end of the 19th and beginning of the 20th centuries, on Kronverksky Prospekt, near the Nikolaevsky (as the Lieutenant Schmidt Bridge was called until 1918) and Tuchkov Bridges, by order of the wealthy merchant Alexandrov, who owned the market on Kronverkskaya Street on the Petersburg side, three identical toilets were built according to the project of architect A. I. Zazersky in the form of small mansions with towers, spires, and patterned brickwork — like miniature fairy-tale castles."
The toilet near the Tuchkov Bridge was apparently demolished even before the start of the Great Patriotic War, and now we will probably never know how much truth and how much fiction there is in this story about the three toilets.
However, the other two toilets, not surrounded by legends, have been preserved. They were built according to the same Zazersky project in 1902 in Alexandrovsky Garden and on Theater Square; the latter is sometimes jokingly called the "small Conservatory" because of its proximity to the Conservatory building.
It should be added that building a toilet wherever someone fancied was practically impossible. One had to apply to the city administration with a proposal about the necessity to erect a public latrine, request the purchase of a land plot for this, and justify such an unusual desire. This proposal, if recognized as justified, could be passed to the City Duma, which could allocate funds for construction or refuse. Alexandrov built the toilet at his own expense, which perhaps inclined the Duma to make an unconventional decision. However, merchant A. Kutuzov, who in 1906 wished to donate 18,000 rubles to the city treasury for the construction of a toilet in Catherine Garden, was decisively refused. The idea to place a latrine there came to Kutuzov a year earlier. For a whole year, the merchant was obsessed with the idea of building not only a toilet but also a pavilion where snacks and drinks would be sold (that was the catch of his plan!). Finally, the matter moved forward: in early summer 1906, Kutuzov placed advertisements in the newspaper seeking contractors for the construction. "Kutuzov is already making himself at home here," wrote a journalist from the Petersburg Leaf. "He ordered, with the permission of the city administration, the removal of several trees and threatens to destroy two more trees adorning the square — an oak and an elm. And he was about to uproot them, but was stopped by the city gardener."
Sources:
Mikhail Kuraev. "Night Watch. Nocturne for Two Voices with the Participation of VOHR Shooter Comrade Polubolotov"
https://dzen.ru/a/X4BuXFwrNAPOvXKI
https://www.citywalls.ru/house23305.html