Animal Management Unit

This is the creation of fanfic author A.A. Pessimal and does not exist in the canon - although with the expansion of the Assassins' Guild school, it is a logical development as Filigree Street cannot contain everything.
The Animal Management Unit at the Assassins' Guild School was the size of a small warehouse. It represented a major investment for the Guild, but Johanna had argued for it, on the grounds that in the normal course of things, the current dedicated facilities at the old Guild School were too small and too outdated to sustain a breeding programme for those animal species the Guild normally cultivated for its own rather specialised purposes. A more holistic approach was needed, she had argued, which in the long run would save the Guild money, as well as providing an invaluable teaching and research facility.
Rather than breeding tree frogs twenty or thirty at a time, why not have a simulated natural habitat for them, which included ample supplies of their prey animals, so that at any one time the Guild could be sure of a couple of hundred to be culled and processed? This would be more economic, as well as providing the appropriate botany for classroom study without the time and expense of sending a field trip to Howondaland. Gathering them in would also provide a useful practical training exercise for students.
Similarly, amongst those useful animals the Guild had always bred, in a pretty much ad-hoc way, similar management programmes could be instituted for those species of scorpions, spiders, and tropical arachnids which had always been so useful and instructive for the Assassins' Guild. And a tropical habitat involved tropical plants. Given time, the Guild could have some of the finest species of poisonous flowers, carnivorous plants and lethal flora of any college in the temperate zone. This also meant income from selling surplus products, or selling and trading in rare plants. While botany was not Johanna's primary field of study, she was sure Mrs Bellamy, the botany mistress, would support her idea, and perhaps be so kind as to help fine-tune the details? And of course Mr Mericet, the Poisons master, would welcome an ample, practically guaranteed, flow of raw material for his classes, as well as a one-stop-shop for graduate Assassins needing to replenish their personal stocks with successful contract completions in mind. And those really exotic ingredients occasionally required by Miss Sanderson-Reeves, the Domestic Science mistress, might also be produced in house.
As a self-contained self-supporting unit, food animals for larger predatory species would also be bred here, and mice, toads and common frogs would also, of course, be in ready supply for dissection by biology students. This spared the Guild having to buy them in from outside.
Description:-
And then there was the A.M.U. on Short Street,  a modern building, strictly functional and without much external ostentation. From the outside it looked like a factory or a warehouse. But the sounds and smells suggested a city farm, or a small menagerie. The building was on three floors to best utilise the site, and the roof was flat. This was intentional: the roof gardens and greenhouses were used to cultivate the very special and exotic sort of plants that the Assassins' Guild had always taken a botanical interest in.
The basement largely housed storage facilities, most of the Aquarium for river and sea lifeforms, and for those species of animals and plants which were nocturnal, from the very deepest seas (in pressurised tanks) or simply not tolerant of too much daylight. The Guild was interested in quite a lot of these.
On the ground floor, the space was exclusively taken up by animal habitats, vivariums, cages, tanks and the Aviary. In fact, it looked as if the building were built around the Aviary, whose cages soared through all three floors and up through the roof. This allowed the captive birds a necessary and important third dimension of height, and they could be observed from all three lower floors and on the roof.
More animal habitats and tanks existed on the second floor, but here part of the space was taken up with laboratories, demonstration rooms, storerooms and classrooms. On the top floor, there were more classrooms and lecture rooms, as well as supporting infrastructure. Clever design allowed rainwater landing on the roof, where it did not nourish the plants, to run down collecting channels and to be collected in a large tank on the third floor for use elsewhere in the building. It rained a lot in Ankh-Morpork: running out of water was not normally a problem.
Finally, there was a small courtyard outside allowing for Doctor Davinia Bellamy's Maximum Security greenhouses and hothouses, where the more restive and troublesome examples of Mother Nature's floral bounty were imprisoned. Only those students trained and experienced in threatening the plants were allowed in here, and then only in pairs, and then only when wearing protective clothing.
As Doctor Davinia Bellamy (PhD, Brin) pointed out to her students, this was Botany and Ecology for Assassins.
Extract from'' The Discworld Tarot ''(Death):-
Doctor Davinia Bellamy walked the aisles of the Animal Management Unit, humming a cheerful tune. While the buiiding was called the Animal Management Unit, the vision was that those animals of value and worth to the Guild of Assassins should be reared and nurtured in conditions as close as possible to those in their home environments. Thus, the Red-Bellied Tarantulas and the Monkey-Eating Spiders normally found in jungles in deep Paraquat and Tezuman lived their lives perfectly happily in jungle trees in a sealed habitat, also inhabited by prey species and a wide selection of native flora. Several species of the famous Tree Frogs lived in a bromeliad paradise which simulated the conditions to be found in the canopy of a rain forest: to reproduce this at ground level in Ankh-Morpork had been one of the initial challenges for the Guild School's Natural History Department. Davinia's expertise was in botany and the cultivation of rare and difficult plants. She had helped design and refine many of the habitats, and her responsibility was the ongoing viability of the exotic flora. She was particularly pleased with the vivariums and herpetology tanks established for the impressive range of snakes and serpents kept by the Guild. She felt these were masterpieces of collaboration between herself and her colleague, Miss Smith-Rhodes, who nurtured the animals. She was just jolly glad she didn't have to feed the snakes, although this duty was routinely delegated to young student Assassins as an additional grading exercise. As the snakes, whether venomous or constrictors, required live food, the teaching Assassins monitored their students for signs of undue squeamishness, over-enthusiasm (1), or worst of all in the presence of dangerous animals, over-confidence.
The AMU has the contract to breed and supply snakes, scorpions and spiders to replenish the  mime artist detention facilities beneath the Patrician's Palace.