Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_67642 ( "Name" text, "Height of bridge structure" text, "Longest Span" text, "Type" text, "Opened" real, "Location" text )

### Question ###
How tall is the Anqing Bridge which opened prior to 2011?

### Accurate SQL ###

SELECT "Height of bridge structure" FROM table_67642 WHERE "Opened" < '2011' AND "Name" = 'anqing bridge'