Answer
$1026$ ft
Work Step by Step
The building is built perpendicular to the ground level,
so we have a right triangle with
$\theta=11^{o}$,
adjacent leg of $1$ mile = $5280$ ft,
and the height ($h$) of the building as the leg opposite to $\theta$
$\displaystyle \tan 11^{o}=\frac{h}{5280}$
$ h=5280\tan 11^{o}\approx1026.32803225\approx 1026$ ft
