What preposition to use with "liegen"?

Question

From Das einfache Leben:

Die Fenster lagen zu ebener Erde

That struck me as a weird construction, but then I'm still learning the language, so I searched for examples of liegen zu in Deutschewelle and I only found

• liegen zu + infinitive verb (lassen, unterschätzen).
• liegen zu with zu = too.

Neither of which is the case of the book, which uses

• liegen zu something

so as to describe that two things are level.

So my question is: Is "liegen zu" still used nowadays to describe two things that are level, or is that obsolete usage? Are there valid alternatives? I'd have tried "liegen an" in the example phrase.

Answer 1

This is not a trait of the verb liegen, but rather a relatively rare use of the preposition zu denoting not a movement, but rather a relative position - totally independent of what verb is used:

• eine Wohnung zu ebener Erde
• zu Tisch sitzen
• er stand zu meiner Rechten
• Truppen zu Wasser und zu Lande ...

This usage is close to a relatively elevated (and, somewhat archaic, and even rarer) usage of zu as in

• das Münster zu Freiburg
• in ihrem Elternhaus zu Odense (Mann, Zauberberg)

and the usage of zu in titles of nobility as in

• Karl-Theodor von und zu Guttenberg

Answer 2

After looking at DWDS I would agree, that this is a dated combination and no longer used with notable frequency.

Checking your source I have to mention that your first finding combines two actually two very different constructs:

• liegen lassen is a fixed phrase of not taking care of an issue
• die vor uns liegen, zu unterschätzen: here the correctly identified infinitive is in a separate clause and unrelated to liegen; the relevant phrase is vor uns liegen ("Don't underestimate problem, which we expect to become pressing soon"), so vor can be considered a typical preposition indicating local/time relation. Similar prepositions in frequent use are auf, hinter, unter.