NYC Townhouse without a basement???

[Darrick Lowe]

I just visited an old, pre-war townhouse multi-family, and the boiler and water heater were on the first floor in the back. When I asked why they weren't in the basement, they said the building doesn't have a basement. Is that possible? I've never heard of that before.  The agent said that he may have heard that this was common for the entire block.  But I figured it had to have at least an oil tank in the basement at some point. Could someone just have filled the basement with sand and boarded it up, or is it possible that the foundation is built on ground level?  If there was an old oil tank in the basement, could this be an issue in the future?