I have the Monroe Models cast plaster stone arch bridge and like it very much – good quality plaster and a good casting with no bubbles or other flaws. They sent me an email alerting me to the fact that they are moving – and also retiring a few of their models. In HO this is the art deco bridge, the large concrete arch culvert, and the concrete bridge. Their N scale page shows some retired models as well. The soon to be retired models are shown on their webpage at sale prices: This is just the HO page
http://monroemodels.us/hoscale.htm
Dave Nelson