Notice how the color of the tiling in this 19th century mikveh mimics the beautiful color of the water below. This mikveh was added to the Portuguese Synagogue's complex in the late nineteenth century. Originally there were five mikva'ot added to this wing of the complex: two first class baths, and three second class baths. This remaining mikveh is one of the second-class mikva'ot. Plans for these mikva'ot drawn by W. Nijhoff (architect) in 1892 are available online. Also available online are plans made in 1891 by H. Moeton Jr. Architect (but apparently not used) for baths to be built on the other side of the complex. The design that didn't get chosen also had first and second class baths, waiting rooms, and toilets. In both Moeton's design and the design that was used, the first class baths are on the end of the row towards the wealthier neighborhoods while the second class baths are nearer to the poorer neighborhood. For a lovely analysis of the relations between the poor and wealthy in Amsterdam's Sephardic community, see Tirtsah Levie Bernfeld's Poverty and Welfare among the Portuguese Jews in Early Modern Amsterdam.
Links:
Bernfeld's book: http://www.littman.co.uk/cat/leviebernfeld-poverty.html