他们当时没有现代工人和工程师拥有的机器.
that是关系代词,引导定语从句,在这里不翻译
the kind of machinery是先行词,后面的that引导的定语从句修饰先行词,其实就相当于一个很长的形容词“现代工人和工程师拥有的...”
主句是They did not have the kind of machinery
从句是that builders and engineers have today