https://stackoverflow.com/questions/47961310/how-to-stack-multiple-images-in-bootstrap-4-carousel?rq=1
<div id="gallery" class="carousel slide" data-ride="carousel">
<div class="carousel-inner">
<div class="carousel-item active">
<div class="row">
<div class="col">
<img class="img-fluid" src="http://via.placeholder.com/800x450/caa8f5/ffffff?text=Image+1" alt="Image 1"/>
</div>
<div class="col">
<img class="img-fluid" src="http://via.placeholder.com/800x450/9984d4/ffffff?text=Image+2" alt="Image 2"/>
</div>
<div class="col">
<img class="img-fluid" src="http://via.placeholder.com/800x450/592e83/ffffff?text=Image+3" alt="Image 3"/>
</div>
<div class="col">
<img class="img-fluid" src="http://via.placeholder.com/800x450/230c33/ffffff?text=Image+4" alt="Image 4"/>
</div>
<div class="col">
<img class="img-fluid" src="http://via.placeholder.com/800x450/b27c66/ffffff?text=Image+5" alt="Image 5"/>
</div>
</div>
</div>
<div class="carousel-item">
<div class="row">
<div class="col">
<img class="img-fluid" src="http://via.placeholder.com/800x450/f35b04/ffffff?text=Image+6" alt="Image 6"/>
</div>
<div class="col">
<img class="img-fluid" src="http://via.placeholder.com/800x450/f18701/ffffff?text=Image+7" alt="Image 7"/>
</div>
<div class="col">
<img class="img-fluid" src="http://via.placeholder.com/800x450/f7b801/ffffff?text=Image+8" alt="Image 8"/>
</div>
<div class="col">
<img class="img-fluid" src="http://via.placeholder.com/800x450/7678ed/ffffff?text=Image+9" alt="Image 9"/>
</div>
<div class="col">
<img class="img-fluid" src="http://via.placeholder.com/800x450/3d348b/ffffff?text=Image+10" alt="Image 10"/>
</div>
</div>
</div>
</div>
<a class="carousel-control-prev" href="#gallery" role="button" data-slide="prev">
<span class="carousel-control-prev-icon" aria-hidden="true"></span>
<span class="sr-only">Previous</span>
</a>
<a class="carousel-control-next" href="#gallery" role="button" data-slide="next">
<span class="carousel-control-next-icon" aria-hidden="true"></span>
<span class="sr-only">Next</span>
</a>
</div>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css" rel="stylesheet"/>
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.3/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js"></script>