Los Filtros de Lindley

Lindley Filters are one of three hydraulic networks, the largest and oldest, and can only be visited on open days (in July and August) by invitation or through an agreed group visit. It's highly protected because it provides drinking water and is at risk from terrorists or other damage. If all you can do is to walk around the outside it's very nice. It has supplied water to the inhabitants of Warsaw since mid-1886, though like everything in Warsaw, it suffered extremely serious damage during the Nazi bombing and the Warsaw Uprising, therefore, the city was without water for almost a year (1944-45).