#MATL, 15 bytes

'_|__'700:)70e!

Of course, you can Try it online! Explanation:

'_|__' % Put a brick on the stack
700    % 700 times
:)     % Makes a happy mason...
70e!   % Secret freemason code

OK, actually, it works as follows:

'_|__' % Put the first bit of the string on the stack
700:   % Put 1, 2, ..., 700 on the stack as array
)      % Index into the string, modularly. Result: '_|___|__ ... __'
70e    % Reshape into 70 rows (and consequently, 10 columns)
!      % Transpose to get the desired output.

MATL, 15 bytes

'_|__'700:)70e!

Of course, you can Try it online! Explanation:

'_|__' % Put a brick on the stack
700    % 700 times
:)     % Makes a happy mason...
70e!   % Secret freemason code

OK, actually, it works as follows:

'_|__' % Put the first bit of the string on the stack
700:   % Put 1, 2, ..., 700 on the stack as array
)      % Index into the string, modularly. Result: '_|___|__ ... __'
70e    % Reshape into 70 rows (and consequently, 10 columns)
!      % Transpose to get the desired output.

#MATL, 15 bytes

'_|__'700:)70e!

Explanation:

'_|__' % Put a brick on the stack
700    % 700 times
:)     % Makes a happy mason...
70e!   % Secret freemason code

OK, actually, it works as follows:

'_|__' % Put the first bit of the string on the stack
700:   % Put 1, 2, ..., 700 on the stack as array
)      % Index into the string, modularly. Result: '_|___|__ ... __'
70e    % Reshape into 70 rows (and consequently, 10 columns)
!      % Transpose to get the desired output.

#MATL, 15 bytes

'_|__'700:)70e!

Of course, you can Try it online! Explanation:

'_|__' % Put a brick on the stack
700    % 700 times
:)     % Makes a happy mason...
70e!   % Secret freemason code

OK, actually, it works as follows:

'_|__' % Put the first bit of the string on the stack
700:   % Put 1, 2, ..., 700 on the stack as array
)      % Index into the string, modularly. Result: '_|___|__ ... __'
70e    % Reshape into 70 rows (and consequently, 10 columns)
!      % Transpose to get the desired output.